Beverley Hughes approved a secret fast-track immigration process for thousands applying for UK passports, it has been revealed.

Applicants at the Immigration and Nationality Directorate's Liverpool office were only required to submit photocopies of their passports, rather than original travel documents.

Of 9,000 cases decided under the new process, 8,135 were approved.

The move applied only to those already residents in the UK, through marriage or the use of work permits, and was designed to clear a backlog of 29,000.

"All applications had police criminal record checks, standard immigration checks and where necessary, further security checks," said a Home Office spokesman.

"It was always possible under the criteria for case workers to request a passport if they had reason to doubt the information on the application.

"Case workers estimate this has been done in about 20 per cent of cases."

 Downing Street confirmed Hughes still had the support of the prime minister.

The official spokesman claimed the issue had been distorted.

"It is not as though people are being given citizenship with no checks whatsoever," he said.

"We're talking about people who are entitled to be here. There has always been an element of discretion."

But the announcement comes after calls for the immigration minister to resign, after a whistleblower revealed that officials in Sheffield had waived checks on applicants from eastern Europe.

Speaking in the Commons, Hughes insisted that she did not approve that particular change in procedure.