Image caption Protesters descended on the embassy in Belgrave Square early on Saturday morning

Six people were arrested during a protest at the Syrian embassy in London overnight, police say.

The Met said about 150 protesters had gathered at 02:00 GMT after reports of more than 200 people being killed by shelling in the Syrian city of Homs.

Five people remained in custody after being arrested for forcing entry into the embassy, and the sixth for assaulting an officer.

Demonstrators said police prevented them from leaving the protest site.

BBC correspondent Andrew Plant said he saw about 30 protesters being held in a cordon, with no signs of trouble.

Reports of the bloodshed in Homs, which cannot be independently verified, come as the UN Security Council prepares to vote later on a resolution backing an Arab League peace plan for Syria.

The draft resolution calls on President Bashar al-Assad to hand power to a deputy to oversee a transition.

'Massacre'

Anass Toma, a Syrian MBA student, said he had attended the protest in Belgrave Square over the "massacre" in Homs.

Mr Toma told BBC News: "We came to the embassy because there were 300 people killed in Syria today. People are angry. I'm worried about the situation back home. I've been in London two years but I'm Syrian, from Aleppo.

They say that an officer was assaulted, and that until they find who assaulted him, they're not going to let protesters leave the kettle Fazel Hawramy, Syrian protester

"We don't know what message the Syrian regime is giving out with this massacre today - given the UN Security Council vote... we don't really understand what they're doing. But we must stop the bloodshed in Syria."

Another demonstrator Fazel Hawramy said between 100 and 150 protesters at the embassy were "kettled" by police and prevented from leaving.

"They say that an officer was assaulted, and that until they find who assaulted him, they're not going to let protesters leave the kettle," he told the BBC.

He said only one family and a few women had been allowed to leave, with most people sitting quietly and listening to the Koran being read.

A Met spokesman said officers were at the scene and appropriate policing was in place.

Ronan McNern, from the Occupy London movement, said he went to the embassy to support the Syrians' cause and saw 150 people surrounded by a ring of about 60 officers.

"The protesters are keeping their spirits up by singing, dancing and playing drums, and they seem to be free to leave the ring. Some of them are waving Syrian flags," he said.

Paint appeared to have been thrown on an embassy door, he added.

Protest call

Syrian activists in Cairo have urged people to protest outside Syrian embassies around the world, and there have also been demonstrations in the US, Sweden, Spain and Germany.

Alexander Page, in Cairo, tweeted: "We are going to raid #Syria'n embassies around the world, this is our duty to our people, they are being massacred right now."

Syria has been gripped by nationwide protests against President Assad's regime for almost a year.

The UN stopped estimating the death toll after it passed 5,400 in January, saying it was too difficult to confirm numbers.

The Syrian government has denied carrying out attacks against civilians but says at least 2,000 members of its security forces have been killed fighting "armed gangs and terrorists".