American judoka Nick Delpopolo was expelled from the Olympic Games today after a positive drugs test and admitted he had eaten food which contained marijuana.

Delpopolo insisted he had not known the unidentified food contained the banned substance, but that was not sufficient as a defence.

The 23-year-old competed in the men's 73kg division and was tested on 30 July after his loss to Mongolian Nyam-Ochir Sainjargal in the repechage stage.

The International Olympic Committee said Delpopolo tested positive for 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid, which is connected to marijuana consumption.

According to the IOC ruling, Delpopolo "explained that his positive test was caused by his inadvertent consumption of food (prior to his leaving for the London Olympic Games) that he did not realise had been baked with marijuana".

Delpopolo has apologised to the United States Olympic Committee and team-mates and, according to the IOC, "indicated that he was embarrassed by this mistake".

In a statement, the IOC said: "The International Olympic Committee today announced that it has disqualified American judoka Nicholas Delpopolo from the men's 73kg judo event of the Games of the XXX Olympiad in London."

The IOC disciplinary commission that heard the case stated that Delpopolo should have his seventh-place finish rescinded, return his diploma for competing in the Games and have his accreditation withdrawn.

He will travel home to the United States tomorrow.

The International Judo Federation have been instructed to modify their results and "consider any further action within its own competence".