Protesters angered by China's crackdown in Tibet have disrupted the Olympic torch relay through London.

British police and Chinese security officers swarmed around protesters in west London Sunday when an activist tried to grab the torch from a relay runner. Other protesters, some draped in Tibetan flags, tried to douse the flame with a fire extinguisher. Police said 25 people were arrested, including three who tried to board a relay bus near the start of the run in northwest London.

Demonstrators at the site where Chinese ambassador Fu Ying was to carry the torch forced authorities to reroute the procession through London's Chinatown.

British Prime Minister Gordon Brown briefly greeted the torch outside of his Downing Street residence, as police and pro-Tibet demonstrators clashed just meters away.

Some celebrities scheduled to carry the torch have withdrawn from the ceremony in protest over Chinese policies.

The torch arrived in London Saturday from St. Petersburg, Russia and heads to Paris from London. It is scheduled to travel through international cities and every Chinese province before the Olympics begin in August.

London is to host the next summer Olympics in 2012.