25 July 2012 Last updated at 19:04 ET
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Graphic unverified amateur footage shows a man in Qaboun, Damascus, going house-to-house discovering bloodied corpses, as Jim Muir reports
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The US has confirmed the defection of two more senior Syrian diplomats, amid mounting pressure on the regime of President Bashar al-Assad.
Syria's representatives in the United Arab Emirates and Cyprus - who are husband and wife - are reported to have fled to Qatar.
It comes amid intensifying clashes in the key city of Aleppo, where troops are trying to halt a rebel advance.
UN members have traded more accusations of blame amid the diplomatic impasse.
Earlier UN Secretary General Ban Ki-moon urged the world to "act now to stop the slaughter", but Security Council members remain deadlocked over what action it should take.
The Syrian government has rushed troops and tanks to Aleppo, Syria's second city and commercial centre, which was seized by rebels.
Continue reading the main story[h=2]At the scene[/h]
Ian Pannell BBC News, Syria
The battle for Aleppo is now raging and it is one neither side can afford to lose. The historic city is not only the largest in the country but its economic heart. The government derives material support from its merchant class and vital industries that supply the rest of the country.
The stakes could not be higher. For the armed opposition, losing would be a disastrous setback that, at the very least, could neuter their revolution for months. For President Bashar al-Assad, losing Aleppo could be the tipping point that presages the downfall of his government.
Despite their confidence and commitment, the rebels remain vastly outgunned and - with reinforcements from the army - outmanned, and it is hard to see how they can prevail. But many people here are desperate for the rebels to succeed.
One activist based in the city, Mohammed Saeed, told Associated Press news agency they were expecting a big assault to try to reassert government control.
The heightening of the crisis is causing regional concern, say correspondents, amid a growing exodus of refugees and fears the fighting could draw in Syria's neighbours.
'Days numbered'"We can confirm the defections of Syrian ambassadors to both the UAE and Cyprus," White House spokesman Jay Carney told reporters aboard Air Force One, according to AFP news agency.
Mr Carney said the move showed that "senior officials around the Assad inner circle are fleeing the government because of the heinous actions taken by Assad against his own people, and the recognition that Assad's days are numbered".
The diplomats in question are Lamia Hariri, Syria's charge d'affaires in Cyprus, and her husband Abdel Latif al-Dabbagh, ambassador to the UAE.
A military attache at the Syrian embassy in Oman - Mohammed Tahseen al-Faqir - is also reported to have defected.
Earlier this month, Nawaf Fares, Syria's ambassador to Iraq, left for Qatar.
A senior state department official told AFP: "These defections serve as a reminder that the bottom is starting to fall out of the regime. It is crumbling and losing its grip on power."
Meanwhile, the BBC's Ian Pannell in Aleppo says the city is now the focus of a battle which neither regime nor opposition forces can afford to lose.
He says restive neighbourhoods are being pounded by artillery, mortars and helicopter gunfire, and there are multiple reports of reinforcements heading to the city.
The fighting has caused renewed regional concern, with Turkey tightening its border controls with Syria, though it says it will allow refugees to get through.
Continue reading the main storyThousands of refugees have already sought shelter in Turkey, Lebanon, Jordan and Iraq.
Meanwhile, AP reported Israelis were rushing to get government-issue gas masks on Wednesday, following a Syrian threat on Monday that it would employ chemical weapons against external attackers.
On Wednesday, the UN's Ban Ki-moon urged world leaders to halt the slaughter in Syria.
But further bitter accusations of blame followed within the UN Security Council, which has seen three resolutions blocked by Russia and China.
"The Syrian people will pay the price for this failure [to act]," Germany's UN ambassador Peter Wittig told a Security Council debate on the Middle East on Wednesday.
But Russia envoy Vitaly Churkin retorted that pledges by some Western powers to take steps to support the Syrian opposition outside the council "contributes and leads to an escalation of confrontation".
Send your pictures and videos to [email protected] or text them to 61124 (UK) or +44 7624 800 100 (International). If you have a large file you can upload here.
Read the terms and conditions
Graphic unverified amateur footage shows a man in Qaboun, Damascus, going house-to-house discovering bloodied corpses, as Jim Muir reports
Continue reading the main story
The US has confirmed the defection of two more senior Syrian diplomats, amid mounting pressure on the regime of President Bashar al-Assad.
Syria's representatives in the United Arab Emirates and Cyprus - who are husband and wife - are reported to have fled to Qatar.
It comes amid intensifying clashes in the key city of Aleppo, where troops are trying to halt a rebel advance.
UN members have traded more accusations of blame amid the diplomatic impasse.
Earlier UN Secretary General Ban Ki-moon urged the world to "act now to stop the slaughter", but Security Council members remain deadlocked over what action it should take.
The Syrian government has rushed troops and tanks to Aleppo, Syria's second city and commercial centre, which was seized by rebels.
Continue reading the main story[h=2]At the scene[/h]
The battle for Aleppo is now raging and it is one neither side can afford to lose. The historic city is not only the largest in the country but its economic heart. The government derives material support from its merchant class and vital industries that supply the rest of the country.
The stakes could not be higher. For the armed opposition, losing would be a disastrous setback that, at the very least, could neuter their revolution for months. For President Bashar al-Assad, losing Aleppo could be the tipping point that presages the downfall of his government.
Despite their confidence and commitment, the rebels remain vastly outgunned and - with reinforcements from the army - outmanned, and it is hard to see how they can prevail. But many people here are desperate for the rebels to succeed.
One activist based in the city, Mohammed Saeed, told Associated Press news agency they were expecting a big assault to try to reassert government control.
The heightening of the crisis is causing regional concern, say correspondents, amid a growing exodus of refugees and fears the fighting could draw in Syria's neighbours.
'Days numbered'"We can confirm the defections of Syrian ambassadors to both the UAE and Cyprus," White House spokesman Jay Carney told reporters aboard Air Force One, according to AFP news agency.
Mr Carney said the move showed that "senior officials around the Assad inner circle are fleeing the government because of the heinous actions taken by Assad against his own people, and the recognition that Assad's days are numbered".
The diplomats in question are Lamia Hariri, Syria's charge d'affaires in Cyprus, and her husband Abdel Latif al-Dabbagh, ambassador to the UAE.
A military attache at the Syrian embassy in Oman - Mohammed Tahseen al-Faqir - is also reported to have defected.
Earlier this month, Nawaf Fares, Syria's ambassador to Iraq, left for Qatar.
A senior state department official told AFP: "These defections serve as a reminder that the bottom is starting to fall out of the regime. It is crumbling and losing its grip on power."
Meanwhile, the BBC's Ian Pannell in Aleppo says the city is now the focus of a battle which neither regime nor opposition forces can afford to lose.
He says restive neighbourhoods are being pounded by artillery, mortars and helicopter gunfire, and there are multiple reports of reinforcements heading to the city.
The fighting has caused renewed regional concern, with Turkey tightening its border controls with Syria, though it says it will allow refugees to get through.
Continue reading the main storyThousands of refugees have already sought shelter in Turkey, Lebanon, Jordan and Iraq.
Meanwhile, AP reported Israelis were rushing to get government-issue gas masks on Wednesday, following a Syrian threat on Monday that it would employ chemical weapons against external attackers.
On Wednesday, the UN's Ban Ki-moon urged world leaders to halt the slaughter in Syria.
But further bitter accusations of blame followed within the UN Security Council, which has seen three resolutions blocked by Russia and China.
"The Syrian people will pay the price for this failure [to act]," Germany's UN ambassador Peter Wittig told a Security Council debate on the Middle East on Wednesday.
But Russia envoy Vitaly Churkin retorted that pledges by some Western powers to take steps to support the Syrian opposition outside the council "contributes and leads to an escalation of confrontation".
Send your pictures and videos to [email protected] or text them to 61124 (UK) or +44 7624 800 100 (International). If you have a large file you can upload here.
Read the terms and conditions