Bolt gets 3rd gold in relay world record

Usain Bolt completed a second successive Olympic golden sprint treble as he anchored Jamaican 4x100 metres relay team to victory in a world record time on Saturday night.

Bolt's third triumph on the final night of track at the Games came after Britain's Mo Farah brought the house down by securing a middle distance double for Britain with 5000m gold.

Keshorn Walcott of Trinidad and Tobago won a first men's throwing event for the Caribbean with javelin gold and Allyson Felix got her third London gold as part of the US 4x400m relay team.

Other golds went to Russians Olga Chicherova (high jump) and Mariya Savinova (800m).

Nesta Carter, Michael Frater, Yohan Blake and Bolt clocked a world record 36.84 seconds in the sprint relay, smashing their previous mark of 37.04 seconds from September 4, 2011, at the world championship in Daegu, South Korea.

The US got silver in 37.04 and Trinidad and Tobago got bronze in 38.12.

Bolt, 25, won back-to-back 100m, 200m and 4x100m titles 2008 in Beijing and repeated the feat in London to cement his status as the global star in the sport.

As in his 10,000m triumph ago a week ago, Farah led the sprint in the final lap after a pedestrian early stage and cruised home in 13 minutes 41.66 seconds amid a wall of sound from the 82,000 crowd in what was arguably the loudest race in athletics history.

Dejen Gebremeskel of Ethiopia failed to match Farah on the home straight and won silver in 13:41.98. Thomas Longosiwa of Kenya took bronze in 13:42.36.

"It's unbelievable. Two gold medals, who would have thought that?" Farah said. "These two medals are for my two girls who aren't born yet. It could be any day. The doctors said we have 12 days."

Gebremeskel said: "I made a big mistake. I stayed in the pack and struggled to get out easily. When the last lap bell rang the lanes were blocked. By the time I tried to catch Mo it was too late."

The women's 800m seemed to be decided when 2008 winner Pamela Jelimo of Kenya opened up a huge lead on the final back straight.

But she faded dramatically coming onto the home stretch as world champion Saviova roared past for gold in a 2012 world best 1:56:19.

The 2009 world champion Caster Semenya of South Africa snatched silver as at the 2011 worlds in 1:57.23, and Ekaterina Poistogova of Russia pipped Jemilo just before the line to get bronze in 1:57.53.

In the 4x400m, Felix teamed up with DeeDee Trotter, Francena McCorory and 400m winner Sanya Richards Ross to win gold in 3:16.87 minutes. Russia got silver in 3:20.23 and Jamaica took bronze 3:20.95.

Walcott got the javelin gold in a national record 84.58 metres.

Oleksandr Pyatnytsya of Ukraine got silver with 84.51 and the bronze went to Finland's Antti Ruuskanen with 84.12m

Chicherova soared a 2012 world-best 2.05 metres to capture high jump gold after bronze in 2008. Brigetta Barnett of the US had a personal best 2.03m to take silver, and Russia's Svetlana Shkolina earned bronze, also with 2.03m.