Russia's foreign minister said after talks in Damascus today that President Bashar al-Assad was "fully committed" to ending the bloodshed in Syria even as regime tanks pounded the city of Homs for a fourth straight day.

Sergei Lavrov said he had had a "very useful" meeting with Assad and that Moscow was eager to work towards a solution based on an Arab League plan that it had previously criticised.

"We (Russia) confirmed our readiness to act for a rapid solution to the crisis based on the plan put forward by the Arab League," said Lavrov, adding that Syria was also ready to see an enlarged Arab League mission in the country, Russian news agencies said.

The pan-Arab bloc deployed an observer mission to Syria in December to oversee a plan to end bloodshed that has now lasted almost 11 months but suspended it late January after the mission's chief said the violence had reached a new pitch of intensity.

The 22-nation League has since put forward a plan for Assad to hand his powers to Vice President Faruq al-Shara and a national unity government to oversee the preparation of democratic elections.

Lavrov gave no indication in his comments about Assad's political future but said without elaborating that he believed the Syrian regime had heard Moscow's message.

"We have every reason to believe that the signal that we've brought here to move along in a more active manner along all directions has been heard."

Lavrov said Syria was pressing ahead with the slow-moving reform programme promised by Assad in a series of speeches last year and would soon announce the timetable for a referendum on a new constitution to replace the current one which enshrines the dominant role of his Baath party.

"President Assad informed (us) that in the nearest future he's meeting a commission which has been preparing the draft of a new constitution," Russian news agencies quoted him as saying.

"The work has been completed, now the schedule of a referendum on this very important document for Syria will be announced."

The official Syrian Arab News Agency said that Assad, who said last month that the referendum could go ahead as early as March, would receive the panel's recommendations on Wednesday.

State television aired footage of regime supporters waving a sea of Syrian and Russian flags as huge crowds lined the streets to welcome Lavrov.

Many chanted: "Thank you Russia, thank you China," in reference to the two governments' use of their Security Council vetoes last week to block UN action against the Syrian regime.

Ahead of Lavrov's arrival, reports had said he might try to persuade Assad to quit but the regime, which has been rocked by an uprising since mid-March, put on a show of defiance.

Tanks and artillery pounded the flashpoint city of Homs in central Syria for a fourth straight day, killing at least 15 civilians, according to activists, as the interior ministry vowed no let-up in the onslaught against "terrorist groups".

"Operations to hunt down terrorist groups will continue until security and order are re-established in all neighbourhoods of Homs and its environs," pledged an interior ministry statement carried by SANA.

Abu Rami, an activist in the city reached by AFP by telephone from Beirut, said shelling and rocket fire had continued through the night and into the day.

"There are about four blasts every five minutes," he said. "Since this morning the shelling has been concentrated in the neighbourhoods of Baba Amr, Inshaat and Jubar. The humanitarian situation is dire. No one can move around."

At least nine civilians and four soldiers were killed as the army attempted to storm the Khaldiyeh neighbourhood of the city, the Syrian Observatory for Human Rights said. One of the slain civilians was a woman.

Another six civilians were killed in Baba Amr, the Britain-based watchdog added, adding that a total of at least 21 civilians were killed across the country on Tuesday.

Shooting thought to be from outgunned rebels echoed across Baba Amr, a rebel stronghold, through the morning in response to the artillery barrage from besieging troops.

The opposition Syrian National Council joined the Free Syrian Army in issuing an appeal to businessmen across the Arab world to give money to the rebel force to help rectify the imbalance in firepower.

Human rights groups say more than 6,000 people have been killed since the outbreak of the revolt. The UN Children's Fund, UNICEF, said at least 400 children are among the dead.

Moscow sparked Western anger last week by joining Beijing in using its veto at the Security Council, in what US Secretary of State Hillary Clinton called a "travesty."

A day after the United States closed its Damascus embassy, France, Italy amd Spain joined Britain and Belgium on Tuesday in recalling their ambassadors to Syria for consultations.

Turkey, which shared Western anger over the Russian and Chinese vetoes, said it would launch a "new initiative" with like-minded countries which "stand by the Syrian people, not the regime."

The six Arab states of the Gulf announced that they had decided to expel Syria's envoys and withdraw their own from Damascus in protest over the "mass slaughter" of civilians in Syria.