Syria has promised to observe a UN-backed ceasefire starting tomorrow, but its forces kept up fierce attacks on opposition neighbourhoods in the hours before the deadline.
A Syrian defence ministry source quoted on state television today said the army would halt operations tomorrow morning, but would confront "any assault" by armed groups.
The report made no mention, however, of withdrawing troops from urban areas - something that was supposed to start yesterday under a peace plan agreed with international envoy Kofi Annan. And even as the ceasefire pledge was being broadcast, activists were reporting more tanks moving in to a major city.
A spokesman for Mr Annan, mandated by the United Nations and Arab League, said the Syrian government had given the former UN secretary general an assurance it would stop fighting by the dawn deadline he has set for a cessation of hostilities. But he also stressed that troops should pull back.
"Annan, this is your ceasefire," ran the sarcastic voiceover on an activist video that showed a shopping mall engulfed in flames after it was hit in bombardment of the Juret al-Shayah quarter. Sniper fire cracked out incessantly in the background. At least 12 people were killed today, activists said.
Western powers have scorned president Bashar al-Assad's truce pledges to the United Nations-Arab League mediator, but so far the lack of an effective policy to curb the bloodshed, given their own aversion to military intervention and the resistance of Russia and China to any UN Security Council action.
"Far from fulfilling their commitment, the regime has cynically exploited the window of diplomatic negotiations to crack down even harder on its own people," British prime minister David Cameron said during a visit to Indonesia.
He said Mr Annan had reported that Dr Assad's troops were "conducting roving military operations in population centres supported by artillery fire". An estimated 1,000 people had been killed in the past week, Mr Cameron said.
With all hostilities with rebels supposed to end at dawn tomorrow, activist videos posted on YouTube showed bombs crashing into the Khalidiya district of Homs.
Spouts of pulverised debris burst high into the air with each impact and plumes of dust and smoke drifted over the rooftops. The videos could not be verified and the Syrian government bars most independent media from the country.
The Syrian Observatory for Human Rights (SOHR), a British-based activist information organisation, said three people were killed Homs and shelling that went on for an hour killed a man, woman and child in Qusair near the border with Lebanon. Three others were killed outside Damascus.
"Mortar fire started at 7 this morning. I can hear one explosion every five minutes," said activist Waleed al-Fares in Homs, where bombardment killed at least 26 people yesterday.
US secretary of state Hillary Clinton said she would meet Russian foreign minister Sergei Lavrov today to seek a policy change from one of Dr Assad's few foreign friends.
"We will have another go at trying to persuade the Russians that the situation is deteriorating and the likelihood of regional conflict and civil war is increasing," she said.
China expressed "deep worries" about the violence in Syria and called for all sides to respect a ceasefire. Foreign ministry spokesman Liu Weimin also described Mr Annan's work as "an important and rare opportunity" to end the crisis.
Mr Annan's plan, endorsed by the Security Council, is for now the only game in town and the former UN secretary general said it must be given a chance to work.
"If everyone respects it, I think by 6 in the morning (3am Irish time) we shall see improved conditions on the ground," he said in Tehran, where he was asking Syria's staunchest regional ally to support his efforts.
Mr Annan, at a news conference with Iranian foreign minister Ali Akbar Salehi, urged Iran to help resolve the violence and warned of "unimaginable consequences" if it worsened further. "I have received (Syrian) government assurances they will respect the ceasefire," he said, adding: "I believe Iran can be part of the solution."
Mr Salehi said Syrians should be able to have free elections contested by political parties, but reiterated Iran's opposition to any outside interference in Syria's affairs and made clear the Islamic Republic wanted Assad to stay in charge. "The opportunity must be given to the Syrian government to make changes, under the leadership of Bashar al-Assad," he said.
Iran has unstintingly backed Syria, the only Arab nation to support Iran in its 1980-88 war with Iraq and the conduit for Iranian arms to Lebanon's Shi'ite Muslim Hezbollah movement. But the Syrian military has stayed on the offensive, pursuing assaults on several anti-Assad strongholds, instead of pulling back, as Mr Annan's plan required them to do yesterday.
In southern Deraa, birthplace of the 13-month-old revolt against four decades of Assad family rule, activists said many busloads of troops backed by armoured vehicles had flooded the city and were making house-to-house raids.
Activist Omar al-Hariri said he had never seen so many troops: "The army is exploiting the ceasefire to arrest more dissidents than ever and security forces are burning houses."
Anti-Assad rebels have said they will stop fighting if the Syrian military pulls back and ceases fire as promised.
