LONDON (AFP) - A British man who threw a plastic beer bottle onto the track at the start of the London Olympics men's 100 metres final was sentenced on Monday to an eight-week community order.

Ashley Gill-Webb, 34, who suffers from bipolar disorder, was convicted of public disorder last month after he shouted at Jamaican sprinter Usain Bolt and hurled the bottle from an exclusive seating area in the Olypic Stadium.

"Your intention was to target the highest-profile event at the London Olympic and put off Usain Bolt," judge William Ashworth told Gill-Webb as he sentenced him at Thames Magistrates Court in east London.

"The potential harm of triggering a false start was significant. By good fortune, you failed. You did, however, spoil the occasion for some spectators and tarnish the spirit of the Games." Mr Ashworth added that the sentence had been reduced to take into account the effects of Gill-Webb's bipolar disorder.

Gill-Webb, from South Milford near Leeds in northern England, will be electronically-monitored and subject to a 7am to 7pm curfew. He was also ordered to pay a £1,500 (S$2,930) contribution to legal costs.

The father-of-two had pleaded not guilty, arguing that he was suffering from a manic episode at the time of the race on August 5 and had not intended to cause distress.

He had shouted things like, "Usain, I want you to lose" at the world's fastest man and thrown the green plastic Heineken bottle as the sprinters went up into the 'set' position on their starting blocks.

Bolt went on to win the race in 9.63sec, retaining his 100m title.

The court heard during the trial that Gill-Webb had tricked his way into the Olympic Park in east London using an old ticket and had managed to push his way to the front of a prime seating area at the stadium.

Dutch judoka Edith Bosch confronted him after he threw the bottle, the court heard. Olympic volunteers restrained him and he was arrested by police.