Olympic sprint champion Usain Bolt ended his London Games in glorious style today with a third gold and a world record as he anchored Jamaica to victory in a blistering men's 4x100 metres final in 36.84 seconds.

It was the same Jamaican quartet of Nesta Carter, Michael Frater, Yohan Blake and Bolt that had set the previous mark of 37.04 at the world championships in Daegu last year.

"It's always a beautiful feeling to end off like this. We did it last year in the world championships - for me it's a wonderful feeling," Bolt told reporters.

"The team came out and gave their all. I knew a world record was possible."

The United States team of Trell Kimmons, individual bronze medallist Justin Gatlin, Tyson Gay and Ryan Bailey won silver in 37.04 to equal the old record.

"There was energy coming from the blocks and Tyson did a great job on third," Gatlin told reporters. "We did a great job and next year we're going to do an even better race."

Canada finished third but were disqualified for a lane infringement, leaving the athletes in tears on the track as Trinidad and Tobago were awarded the bronze in 38.12.

"We ran a great race and we did everything. This is unfortunate. It sucks," Canada's fourth man Justyn Warner said.

"Everyone dreams about getting a medal and we have just had one taken away."

US lead-off man Kimmons got a flying start and the Americans appeared to have the initial edge but by the third leg Jamaica's 100 and 200 silver medallist Blake came off the bend level with rival Tyson Gay and once Bolt got the baton there was only ever going to be one winner.

To a tumultuous noise, Bolt pulled away from American Ryan Bailey and, for once, kept going all the way to the finish even dipping for the line.

Bolt, who now has six Olympic gold medals from two Games, wanted to keep the baton but track officials would not let him, resulting in boos from the 80-000 strong crowd.

The Jamaicans then went on a lap of honour, high-fiving and kissing members of the crowd.

It was the first time in four global championships that the US men had successfully got the baton round after fluffing changeovers in Beijing four years ago and the last two world championships.

"I can go to sleep now, and you can quote me on that," said US relay coach Jon Drummond

"They did what they came to do - get the stick around. That was what my job description was.

"The guys broke the old world record or tied it, that was phenomenal. Jamaica ran 36.8 and we ran 37.04. What it says to me is it's a record that should have been broken years ago, and these guys possess the ability to go even faster."

- Reuters