A former immigration officer claims that hundreds of illegal immigrants wed in sham marriages after Government officials turned a blind eye to the scandal.
Whistleblower Neville Sprague, 56, alleges he was sacked by the UK Border Agency (UKBA) because he insisted on investigating crimes his department did not want recorded in their statistics.
The former chief immigration officer is taking the agency to a tribunal where he is claiming unfair dismissal.
He told the Daily Mail the shams involved West Africans, mainly from Ghana, who would pay more than £10,000 to marry a British citizen who would also be paid up to £7,000 to take part.
He said: "I amassed evidence of bogus weddings but my managers just did not want to know. They were really keen for me not to investigate.
They kept saying, 'It's not that bad'. I said: 'Yes it is!'."
Immigration minister Damian Green has said the Government is determined to show the country is not a soft touch for those with no right to remain.
Last week the Rev Alex Brown was found guilty of conducting around 360 sham marriages over a period of four years at his church in St Leonards-on-Sea, East Sussex, thought to be the largest scam of its kind.
Mr Sprague, from south Croydon, south London, said he uncovered a similar scam in east London but his bosses ignored his efforts to investigate it properly.
He told the paper: "To do something about it required effort, resources and of course it became another unwelcome statistic."
