Syrian government shelling and offensives against rebel-held towns killed at least 53 civilians across the country yesterday, activists said, as the US posted online satellite images of troop deployments that cast further doubt on whether the regime intends to comply with an internationally sponsored peace plan.

Syrian President Bashar Assad has accepted a ceasefire deadline brokered by international envoy Kofi Annan, which calls for his forces to pull out of towns and cities by Tuesday and for both government and rebels to lay down their arms by 6am local time on Thursday.

But the escalating violence of the past few days has fuelled accusations that Assad is rushing to stamp out as much of the year-old uprising against him as he can before next week’s ceasefire. The Syrian government said it has begun to withdraw forces ahead of the ceasefire but activists say no significant pullouts have taken place and troops, checkpoints and snipers remain in almost all major flashpoint towns and cities.

“They are systematically trying to crush the revolt wherever they can and regardless of the human cost,” said activist Mohammad Saeed in the Damascus suburb of Douma.

US ambassador to Syria Robert Ford said the Syrian government appears to have pulled back some of its forces from towns and cities but in other places has kept in place or simply shifted around troops and armoured vehicles. He said he was basing his information on satellite images before and after the alleged pullouts which were posted on the US Embassy Facebook page yesterday.

Arrests, sweeps, and the artillery bombardment of opposition strongholds have continued, Ford’s statement said.

“This is not the reduction in offensive Syrian government security operations that all agree must be the first step for the Annan initiative to succeed,” the late Friday statement said.

“The regime and the Syrian people should know that we are watching. The regime cannot hide the truth,” it added.

Ford was forced to leave Syria in February citing security concerns, and the US Embassy there was closed indefinitely.

Western leaders along with the Syrian opposition have cast doubt on Assad’s intentions, suggesting he is playing for time and is not serious about the plan, which aims to pave the way for talks between the regime and the opposition on a political solution.

The government has launched offensives in several parts of the country in the past few days in a desperate attempt to crush the rebels.

Opposition groups said at least 53 people were killed across Syria yesterday, most of them in government shelling and clashes in the village of al-Latamneh in the central Hama province. The British-based Syrian Observatory for Human Rights said four people were killed in the nearby Tibet al-Imam area.

An amateur video posted by activists on the Internet showed al-Latamneh residents crying “Allahu Akbar” as they held up a small girl, apparently dead. The video also shows the bodies of several men covered in white sheets lined up on the ground.

In the nearby province of Homs, activists also reported shelling of the rebel-held areas of Rastan, Deir Baalabeh and Qusair, where they said at least three people including a mother and her son were killed.

The Observatory also said 13 unidentified bodies were found in Deir Baalabeh and 10 in Hreitan in the northern province of Idlib.

In other violence, Lebanese security officials said six people were killed and 21 wounded in a rocket attack on a Lebanese bus after it crossed into Syria yesterday. The bus was carrying pilgrims to Iraq and was struck after it crossed the Joussiyeh border crossing in eastern Lebanon into Syria.

The officials said five Syrians and a Lebanese were killed in the attack. It was not immediately clear who fired the rocket, or how many of the dead were on the bus or bystanders.

UN Secretary-General Ban Ki-moon said the 10 April timeline “is not an excuse for continued killing.” In statements made on Friday, he urged the government to “immediately and unconditionally” cease all military actions against the Syrian people.

An offensive in Idlib over the past few days has triggered a massive wave of refugees who crossed the border to Turkey with horrific accounts of mass graves, massacres and burnt-out homes.

Activists have reported about 100 dead in the villages of Taftanaz and Killi, both in Idlib, in recent days.

The escalating violence has dimmed hopes that the fighting, which the UN says has killed more than 9,000 people, will end anytime soon. The country appears to be spiralling toward civil war – a fearsome development that could bring a regional conflagration.

Ambassador Ford urged Assad to allow a UN monitoring force into the country and to give it full access to investigate the regime’s compliance with the peace plan.

On Friday, a small UN advance team headed by a Norwegian major general, Robert Mood, met with Syria’s deputy foreign minister to discuss the ceasefire plans. Mood is to set up a UN monitoring force with 200 to 250 members if the peace plan succeeds.