Syrian forces thrust into the rebellious city of Homs yesterday, killing as many as 100 civilians, as Turkey appeared to be preparing a new diplomatic push against President Bashar al-Assad.

Turkish Prime Minister Tayyip Erdogan - who is at the centre of an initiative uniting Western, Arab and other states that have called for Assad to step down - was due to speak to Russian President Dmitry Medvedev yesterday.

But Erdogan, who described the Russian and Chinese veto of the U N resolution at the weekend as a "fiasco", faces a hard-sell in Moscow.

Russian Prime Minister Vladimir Putin has condemned Western "interference" of the kind seen last year in Libya, as a "cult of violence".

Putin, who first won the presidency after his military assault on the rebel Russian city of Grozny, is expected to return to the Kremlin after an election next month in which he accuses the West of aiding his opponents.

His foreign minister, Sergey Lavrov, who visited Assad in Damascus on Tuesday, said Russia was still opposed to peace talks that were conditional on Assad stepping aside.

A newspaper close to the Erdogan government said Turkey was planning to organise a conference of Arab and Western governments in Istanbul.

A Nato member and rising Muslim power in the region, Ankara is sheltering Syrian rebel army commanders and has spoken of creating safe havens for refugees.

As the diplomatic gears turned, the military offensive in Homs and elsewhere showed no sign of a let-up.

Activists in the city accused militiamen of slaughtering three families in their homes - the sort of incident fuelling fears of a descent into more widespread, Iraq-style sectarian killing.

The day's death toll stood at more than 100, activists said, but the figures could not be independently verified.

The onslaught on Homs, one of the bloodiest of the 11-month-old revolt against Assad, has not slackened, despite a promise to end the bloodshed that the Syrian leader gave to Russia, which saved Damascus from UN Security Council action on Saturday.

In the latest assault on Homs, troops fired rockets and mortars as tanks entered the Inshaat neighbourhood and moved closer to Bab Amro, the district hardest hit by bombardments that have killed nearly 200 people in the past two days, activists and opposition sources said.