"Tragically, we now have another grim reminder that the Council's resolutions continue to be flouted," his letter said, urging members to send Mr Assad a message that there would be "consequences" for his non-compliance.
Western politicians lined up to express their outrage over the latest massacre. William Hague, the Foreign Secretary, said it confirmed "an unanswerable case for a tough UN Security Council resolution" that would trigger mandatory sanctions if Mr Annan refused to end the violence and establish a transitional government.
The circumstances surrounding the bloodletting in the village remained murky, with rebels and the government both blaming each other for the bloodshed.
Tremseh runs along the same sectarian fault line as two other villages – Houla and Qubeir – whose Sunni inhabitants were allegedly massacred by militiamen drawn from Mr Assad's Alawite minority.
Activists with the Sunni-dominated opposition said the latest killings were part of a regime-backed "ethnic cleansing" campaign to wipe out isolated Sunni farming villages in what is traditional Alawite territory.
They claimed that the killings in Tremseh followed a familiar pattern, with government forces shelling the village before loyalist "Shabiha" militiamen rounded up survivors and executed them.
But some opposition figures conceded that the slaughter may have been more spontaneous after rebels sheltering in the village ambushed an army convoy, triggering a government counter-attack.
Dozens of the dead were said to be men of fighting age, with far fewer women and children thought to be among the fatalities than in the previous two massacres.
Vowing to avenge the killings, the rebel Free Syrian Army gave officials in the regime until the end of the month to defect or face an assassination campaign.
For its part, the Assad regime said that 50 people had died but blamed the killings on rebel "terrorists" and foreign journalists.
"The bloodthirsty media, in collaboration with gangs of armed terrorists, massacred residents of Tremseh village to sway public opinion against Syria and its people and provoke international intervention on the eve of a UN Security Council meeting," the state-run SANA news agency said.
With international efforts to secure a hard-hitting Security Council resolution continuing to meet opposition from Russia, Gen Mood called for an end to big-power antagonism.
"For the sake of the Syrian people we now need genuine and effective leadership from the Security Council," he told reporters in his most outspoken comments since taking command in April.
"The Security Council should unite on a plan that meets the aspirations of the Syrian people and is accepted by the parties."
The Syrian opposition also urged the world to unite in action against the Assad regime amid signs that it was losing patience with the West and Mr Annan in particular.
For the first time, the Muslim Brotherhood, the most influential single party within the opposition, said that it held Mr Annan partially to blame for the killings because of his perceived fecklessness in dealing with the regime.
"The Muslim Brotherhood in Syria do no consider Bashar the Beast the only one responsible for this horrific massacre," the movement said in a statement.
"Responsibility for this and for previous massacres also lies with Annan, with the Russians and the Iranians, and all those states which claim they are protecting peace and stability and yet stay silent and skulk away from taking any responsibility."
There was also anger on the streets, with the traditional anti-Assad Friday protests held under the slogan: "Topple Annan, the servant of Assad and Iran".
Summing up the mood among the opposition, one protester banner read: "God hates Assad for shedding innocent blood, Annan's heart which devised wicked plans, and Putin for his lying tongue."
Despite fears that the latest killings would only lead to an increase in the violence that has already claimed an estimated 17,000 lives, there seemed to be little prospect of a diplomatic breakthrough.
Russia, despite the latest massacre, said it would not countenance a resolution imposing sanctions if Mr Assad's government does not halt the use of heavy weapons and withdraw his troops within a ten-day deadline.
Signalling its determination to project public support for Mr Assad, Russia announced that an arms ships prevented from reaching Syria last month after Britain ensured that its insurance cover was withdrawn had again set sail.
The MV Alaed, carrying a cargo of refurbished attack helicopters of the type used in recent attacks, weighed anchor from its port in the Russian Arctic. The vessel previously flew the flag of Curaçao but has now been re-hoisted with the Russian tricolor.
Western politicians lined up to express their outrage over the latest massacre. William Hague, the Foreign Secretary, said it confirmed "an unanswerable case for a tough UN Security Council resolution" that would trigger mandatory sanctions if Mr Annan refused to end the violence and establish a transitional government.
The circumstances surrounding the bloodletting in the village remained murky, with rebels and the government both blaming each other for the bloodshed.
Tremseh runs along the same sectarian fault line as two other villages – Houla and Qubeir – whose Sunni inhabitants were allegedly massacred by militiamen drawn from Mr Assad's Alawite minority.
Activists with the Sunni-dominated opposition said the latest killings were part of a regime-backed "ethnic cleansing" campaign to wipe out isolated Sunni farming villages in what is traditional Alawite territory.
They claimed that the killings in Tremseh followed a familiar pattern, with government forces shelling the village before loyalist "Shabiha" militiamen rounded up survivors and executed them.
But some opposition figures conceded that the slaughter may have been more spontaneous after rebels sheltering in the village ambushed an army convoy, triggering a government counter-attack.
Dozens of the dead were said to be men of fighting age, with far fewer women and children thought to be among the fatalities than in the previous two massacres.
Vowing to avenge the killings, the rebel Free Syrian Army gave officials in the regime until the end of the month to defect or face an assassination campaign.
For its part, the Assad regime said that 50 people had died but blamed the killings on rebel "terrorists" and foreign journalists.
"The bloodthirsty media, in collaboration with gangs of armed terrorists, massacred residents of Tremseh village to sway public opinion against Syria and its people and provoke international intervention on the eve of a UN Security Council meeting," the state-run SANA news agency said.
With international efforts to secure a hard-hitting Security Council resolution continuing to meet opposition from Russia, Gen Mood called for an end to big-power antagonism.
"For the sake of the Syrian people we now need genuine and effective leadership from the Security Council," he told reporters in his most outspoken comments since taking command in April.
"The Security Council should unite on a plan that meets the aspirations of the Syrian people and is accepted by the parties."
The Syrian opposition also urged the world to unite in action against the Assad regime amid signs that it was losing patience with the West and Mr Annan in particular.
For the first time, the Muslim Brotherhood, the most influential single party within the opposition, said that it held Mr Annan partially to blame for the killings because of his perceived fecklessness in dealing with the regime.
"The Muslim Brotherhood in Syria do no consider Bashar the Beast the only one responsible for this horrific massacre," the movement said in a statement.
"Responsibility for this and for previous massacres also lies with Annan, with the Russians and the Iranians, and all those states which claim they are protecting peace and stability and yet stay silent and skulk away from taking any responsibility."
There was also anger on the streets, with the traditional anti-Assad Friday protests held under the slogan: "Topple Annan, the servant of Assad and Iran".
Summing up the mood among the opposition, one protester banner read: "God hates Assad for shedding innocent blood, Annan's heart which devised wicked plans, and Putin for his lying tongue."
Despite fears that the latest killings would only lead to an increase in the violence that has already claimed an estimated 17,000 lives, there seemed to be little prospect of a diplomatic breakthrough.
Russia, despite the latest massacre, said it would not countenance a resolution imposing sanctions if Mr Assad's government does not halt the use of heavy weapons and withdraw his troops within a ten-day deadline.
Signalling its determination to project public support for Mr Assad, Russia announced that an arms ships prevented from reaching Syria last month after Britain ensured that its insurance cover was withdrawn had again set sail.
The MV Alaed, carrying a cargo of refurbished attack helicopters of the type used in recent attacks, weighed anchor from its port in the Russian Arctic. The vessel previously flew the flag of Curaçao but has now been re-hoisted with the Russian tricolor.