The Syrian city of Homs has come under renewed bombardment for the fifth day running - the heaviest so far, residents have told the BBC.

Activists say more than 40 people have died as a result of the new shelling, but this is difficult to verify.

The attacks come a day after President Bashar al-Assad promised the Russian foreign minister in Damascus that he would end violence and start dialogue.

Russia and China blocked a UN Security Council resolution last week.

The BBC's Paul Wood, who is now on the outskirts of Homs with rebel fighters, says most people in the hardest hit areas of the city are huddled indoors, too terrified to venture outside.

A resident of the Baba Amr area of Homs, Omar, told the BBC that the rocket and mortar attacks were indiscriminate.

"Every house here in Baba Amr is a target," he said. "You have to be lucky to survive."

He said a baby was killed when a rocket landed on a nearby house.

Unconfirmed reports claimed that pro-government militiamen known as "shabiha" were going door-to-door and killing indiscriminately.

There are also reports that 18 premature babies died after their incubators failed as a result of power cuts. State TV denied the reports and said Homs hospitals were operating normally.

Our correspondent says the city is full of rumours, with five days of almost constant shelling creating an atmosphere of hysteria and despair.

State TV reported that "armed terrorists" had attacked an oil refinery in the city. The government blames the violence of foreign-backed groups.

Russian visit

On Tuesday the Syrian president told visiting Russian Foreign Minister Sergei Lavrov that he was prepared to co-operate with plans for stability.