LONDON — Police scuffled with protesters as Olympians and dignitaries carried the torch Sunday during a chaotic relay through snowy London.

Demonstrators tried to board a relay bus after five-time Olympic gold medalist rower Steve Redgrave launched procession at Wembley Stadium — presaging a number of clashes with police along the torch's 31-mile journey.

In west London, a protester tried to grab the torch out of the hands of a TV presenter, forcing police to briefly stop the procession as officers detained the man. Another demonstrator tried to snuff out the flame with what appeared to be a fire extinguisher.

Others in the crowd threw themselves at torchbearers running past in official Beijing 2010 Olympics tracksuits, surrounded by a phalanx of security officials jogging alongside them to protect them — and the torch — from protesters.

The protests have forced officials to make unscheduled changes to the relay route, Metropolitan Police said. Thirty people have been arrested.

British Prime Minister Gordon Brown briefly greeted the torch when it arrived outside his Downing Street residence as pro-Tibet demonstrators and police clashed yards away near Britain's Parliament buildings.

Demonstrators swelled in number near the spot where Chinese Ambassador Fu Ying had been expected to carry the Olympic torch. Instead, Fu emerged with the torch in the heart of London's Chinatown, managing to jog unhindered before handing it over to the next participant.

Along the route, hundreds of protesters chanted "Free Tibet!" "Stop killing in Tibet!" and "China, talk to Dalai Lama!"

In London's historic Bloomsbury area, police separated anti-China protesters from flag-waving Chinese who turned out to support their nation and the Olympics.

"There was definitely a bit of an edge," British tennis player Tim Henman, one of the torchbearers, told The Associated Press.

Police Cmdr. Jo Kaye said the incidents were minor. "It's going to be a long day but the torch is progressing on schedule," Kaye told British Broadcasting Corp. television.

Brown himself never handled the torch but watched as Olympic gold medalist Denise Lewis handed it to Paralympic hopeful Ali Jawad. Student Scott Earley Jr., from Glasgow, Scotland, then took the torch from Downing Street, needing help from dozens of police to keep baying mobs from snatching it from him as he ran past Big Ben to Westminster Bridge.

"Everyone was running at you. It was a bit weird," said Earley, 17. "The police had it covered. They told me when to go and what to do."

Later, police hustled a torchbearer onto an official bus after he was surrounded by a 100 activists. The torch then traveled part of the journey toward St. Paul's Cathedral by bus instead, police said.

Activists demonstrating against China's human rights record and a recent crackdown on Tibet have been protesting along the torch route since the start of the flame's 85,000-mile odyssey from Ancient Olympia in Greece to Beijing.

The torch's global tour, the longest in Olympic history, is meant to highlight China's growing economic and political power. But it also has offered protest groups abundant opportunity to draw attention to their concerns.

Metropolitan Police said it was aware of six organizations — including the Free Tibet campaign, the spiritual group Falun Gong and a group calling for democracy in Myanmar — protesting Sunday. Two thousands police officers were deployed to secure the route.

The 80 torchbearers include Olympic champion Kelly Holmes and violinist Vanessa Mae. Several dropped out to protest China's human rights record — including Richard Vaughan, Britain's top badminton player, who said China was not doing enough to stop violence in the Sudanese region of Darfur.

British Chinese residents had hoped for a peaceful torch relay.

"The Olympic Games are very important for all Chinese. In Chinatown, everyone is very anxious to see the torch pass," London Chinese Community Center spokeswoman Annie Wu said before the procession began. "We hope it goes smoothly."

The torch relay is expected to face demonstrations in Paris, San Francisco, New Delhi and possibly elsewhere on its 21-stop, six-continent tour before reaching mainland China on May 4.