Activists say troops killed at least 19 people in some of the bloodiest fighting in Damascus since start of 10-month uprising

Syria launched a major military offensive to seize back parts of Damascus under de facto rebel control on Sunday, a day after the Arab League said it was abandoning its monitoring mission in the face of out-of-control violence.

Government forces killed at least 19 people, activists said, in some of the bloodiest fighting in the capital since Syria's 10-month uprising began. Witnesses inside Damascus described scenes of mayhem, with troops shelling residential areas and fierce house-to-house fighting.

"It's urban war. There are bodies in the street," one activist, speaking from the suburb of Kfar Batna, told Reuters.

Around 2,000 troops, together with at least 50 tanks and armoured vehicles, began a major operation at dawn, when they headed towards the al-Ghouta area in eastern Damascus. The foray was part of a wider offensive against the suburbs of Saqba, Hammouriya and Kfar Batna, activists said.

Video footage showed tanks trundling forward, followed by government soldiers on foot. The army pushed deep into the centre of Kfar Batna. Witnesses reported four tanks in the main square.

Activists said 14 civilians and five insurgents from the opposition Free Syrian Army (FSA) were killed. Gruesome unconfirmed video showed the mangled bodies of what appeared to be civilians caught by mortar or shellfire.

The unprecedented operation appears an attempt to regain the initiative from the rebels, who have grown increasingly bold in recent weeks. The BBC's Middle East correspondent, Jeremy Bowen, discovered the FSA openly manning roadblocks in Damascus last week, just 30 minutes away from Bashar Al-Assad's presidential palace.

The insurgency, which is still raging in towns and cities across Syria - with further protests in Aleppo on Sunday — has now definitively reached the capital. The suburbs are made up of conservative Sunni Muslim towns, surrounded by countryside and farmland, known as the al-Ghouta.

The area has seen large demonstrations demanding the overthrow of Assad and his minority Alawite regime. The Alawite sect has traditionally dominated Syria's government and armed forces.

Locations of clashes in Damascus. Graphic: Paul Scruton

One activist in Saqba suburb told Reuters that mosques there had been turned into field hospitals and were appealing for blood supplies.

"They cut off the electricity. Petrol stations are empty and the army is preventing people from leaving to get fuel for generators or heating," he said.

Sunday's army offensive came after the Arab League said on Saturday that it was suspending its widely-criticised monitoring mission, which has proved incapable of stopping the killing. The League's chief, Nabil Elaraby, flew to New York to try to win support on the UN security council for his peace plan, designed to end the violence through political means.

Under the plan, Assad would step down in favour of his vice-president, allow free and fair elections to take place and a national unity government to be formed. The plan is modelled on the solution to the crisis in Yemen, which saw the country's president, Ali Abdullah Saleh reluctantly hand over power to his deputy, albeit after months of delay. Saleh is now seeking medical treatment in the US.

Syria has categorically rejected the Arab League's plan as "foreign interference". There were also indications that Russia, Syria's closest strategic ally and key military supplier, would not accept it either.

Russia's foreign minister, Sergei Lavrov, said Moscow would not sign off on any deal that forced Assad out. Additionally, Moscow wanted a clear commitment that there would be no Libya-style foreign intervention in Syria, he said.

Speaking shortly before he left Cairo for New York, Elaraby said he hoped to overcome resistance from China and Russia, both of which have veto powers on the security council. "There are contacts with China and Russia on this issue," he said. A Syrian government official, meanwhile, was quoted as saying Damascus was surprised by the League's decision to suspend operations, and interpreted it as an attempt to prepare the way for foreign intervention in Syria. The aim was also to encourage violent armed groups, he suggested.

Assad has repeatedly dubbed the uprising against his rule as the work of terrorists. State news agency SANA reported the funerals on Saturday of 28 soldiers and members of the security forces killed by "armed terrorist groups" in Homs, Hama, Deraa, Deir al-Zor and Damascus province.

Another 16 soldiers were reported killed on Sunday. SANA said six soldiers died in a bombing sout-west of Damascus, while the opposition Syrian Observatory for Human Rights said 10 soldiers were killed when their convoy was attacked in Jabal al-Zawiya in northern Syria.

In Rankous, 20 miles north of Damascus by the Lebanese border, Assad's forces have killed at least 33 people in recent days in an attack aimed at dislodging army defectors and insurgents, locals reported. Rankous is a mountain town of 25,000 people. It has been under tank fire since Wednesday, when several thousand troops laid siege to it, they added.

The foreign secretary, William Hague, said he was deeply concerned by the violence in Syria and the decision by the Arab League to call a halt to its monitoring activities. Hague called on the international community to unite this week and to agree a UN security council resolution that would stop "the killing and the repression of civilians".

France, which has been leading calls for a stronger international response, said the Arab League decision highlighted the need to act.

"France vigorously condemns the dramatic escalation of violence in Syria, which has led the Arab League to suspend its observers' mission," the French foreign ministry said.

"Dozens of Syrian civilians have been killed in the past days by the savage repression undertaken by the Syrian regime … Those responsible for these barbarous acts must answer to their crimes."

The Arab League mission began at the end of last year. Its brief was to observe Syria's supposed implementation of a peace plan, but the plan failed. Gulf states withdrew monitors last week, saying their team could not stop the violence.

In December the UN said more than 5,000 people had been killed in the protests and crackdown. Syria says more than 2,000 security force members have been killed by militants.

On Friday, the UN security council discussed a European-Arab draft resolution aimed at halting the bloodshed. Britain and France said they hoped to put it to a vote next week. Russia joined China in vetoing a previous western draft resolution in October, and has said it wants a Syrian-led political process, not "an Arab League-imposed outcome" or Libyan-style "regime change".