More than 80 migrants were arrested after border police swooped in a crackdown on unlawful working.
Some of those caught were asylum seekers – who are banned from employment here – while others were migrants who has arrived as ‘tourists’.
Half had used fake passports or other false documents to get a job, according to the Evening Standard.
Others were detained for overstaying their visas or working despite being barred from doing so under immigration or asylum rules.
Many of the offenders have already been removed from Britain. The rest are either in custody, awaiting prosecution or facing deportation.
The arrests by the UK Border Agency over the past seven months will fuel the controversy about employment at the Stratford site.
They come in the wake of Gordon Brown’s pledge to provide ‘British jobs for British workers’.
Protesters have accused 2012 bosses of using cheap agency workers, often from overseas, in breach of labour agreements.
There have been further complaints about the small number of locals gaining work on the £9.3 billion project.
The arrests will also raise questions about the number of illegal workers elsewhere in Britain and whether similarly robust monitoring is carried out by other employers.
The UK Border Agency and the Olympic Delivery Authority said the detections were a tribute to the rigorous checks conducted on workers at the 2012 site.
Details of the illegal workers are contained in figures issued by the agency.
They state that between April and late November a total of 84 people either working or seeking employment at the Olympic site were arrested for immigration offences, with half also detained for using false documents.
The largest number were from India, whose nationals accounted for 32 of the total.
There were 12 Nigerians, seven Ukrainians, four Brazilians, four Kosovans, three Moldovans, and two each from Sierra Leone, Albania and Zimbabwe.
The remainder were described as ‘others’.
Officials found workers using the genuine passports of others which were either stolen or borrowed. Some were caught with fake UK visas or had substituted pages in their passports.
Illegal workers had also switched the photograph in another person’s passport.
Announcing the enforcement action, Tony Smith, the UK Border Agency’s Olympics-director, said: ‘The UK Border Agency has officers based permanently at the Olympic site to check the identity of people seeking work and to help ensure the Games are delivered on time, with a workforce legally entitled to be there.
A spokesman for the ODA added: ‘These figures demonstrate our efforts to ensure people working on site are legally entitled to do so.’
In addition to the illegal migrants, eight others who were entitled to work in the UK were arrested for using false documents to obtain work.
Three were Britons, including a journalist who was seeking, unsuccessfully, to expose lax security.
When added to statistics for enforcement action in previous years, which show around 130 arrests, today’s figures take the total of illegal migrants detected at the site to more than 200. Daily Mail (UK)