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

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.

There have been 30 arrests, Metropolitan Police said.

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.

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, forcing a last-minute change of plan. Fu emerged with flame in the heart of London's Chinatown instead, and managed to jog unhindered before handing over the torch to the next participant in the relay.

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

"As an English person, I have a right to stand where I want to on the street," pro-Tibet demonstrator Roger Moulland, 54, from Brighton, said as he was moved away by police.

Hundreds of protesters along the route chanted slogans including "Free Tibet!" "Stop killing in Tibet!" and "China, talk to Dalai Lama."

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

Brown allowed the flame to arrive outside his Downing Street office but never handled the torch. Instead, he watched as Olympic gold medalist Denise Lewis handed it to Paralympic hopeful Ali Jawad.

Seventeen-year-old student Scott Earley Jr., from Glasgow, Scotland, carried the torch from Downing Street, needing help from dozens of police to keep baying mobs from snatching the torch as he ran past Big Ben to Westminster Bridge.

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

Activists demonstrating against China's human rights record and a recent crackdown on Tibet have been protesting along the torch route throughout the flame's 85,000-mile odyssey from Ancient Olympia in Greece to Beijing, host of the 2008 Summer Olympics.

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

"People are traveling from across the country and Europe as well to participate," said spokesman Terry Bettger of the Free Tibet Campaign.

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, participating in protests. The force deployed 2,000 officers along the route.

The 80 torchbearers include Olympic champion runner 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.