Usain Bolt wins third gold medal of London 2012 as Jamaica claim new world record in 4x100m relay final

Double Olympic sprint champion Usain Bolt anchored Jamaica to victory in a blistering men's 4x100 metres final as they retained their title in a world record 36.84 seconds tonight.

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

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 re3cord.

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

It means Usain Bolt has won three gold medals at London 2012, and retained all the titles he won in Beijing four years ago.

Bolt was asked if he could do the 'treble-treble' by winning the 100m, 200m and 4x100m again in four years' time, having achieved the feat first in Beijing and now in London.

He is not convinced it is possible.

Bolt said on BBC1: "I've thought about it but I think it's going to be very hard because Yohan, he's just come into the game and he's running pretty well, and I'm sure there's going to be a lot more cats coming up to run.

"I'm just happy. I'll take it a step at a time."

Asked whether he would run more often in Britain if tax laws change - a factor in him having stayed away in the past - Bolt said: "As soon as the law changes I'll be here all the time.

"I love being here, I have so many Jamaican fans here and it's wonderful."

Reuters/PA