Secret service cleaners - who officially do not exist - have broken with the tight-lipped tradition of the espionage world to fight government plans to axe their jobs.

The group of 50 cleaners from MI6, the Government's overseas intelligence service, who are bound by the Official Secrets Act, approached Harriet Harman, the Labour MP for Peckham, for help. They say they have no written contract and are not able to join a union.

The issue has has come to a head because the Government is planning to privatise the service, forcing cleaners to take redundancy or accept jobs on lower hourly rates of pay.

Ms Harman, said the cleaners were so distressed that they were prepared to risk breaking the law to contact her. 'They are very afraid. They don't know where to turn. They take their responsibility very seriously and don't want to rush around telling everyone about their problems.

She has written to the Prime Minister and the head of the Civil Service exposing what she describes as the shameful way the Government has acted.

'They wouldn't be able to do this with cleaners employed anywhere else in government service,' said Ms Harman. She claims those cleaners being forced to accept redundancy will not receive their full redundancy rights, but can do nothing about it because of the restrictions of the Act.

'The Government is using official secrecy to get away with not having to pay them the money required. Some of these people have been working up to 25 years for MI6. They have to sign the Official Secrets Act.

'Just as MI6 doesn't exist, neither do they.'

Ms Harman argues the cleaners should also have rights under the European directive passed this month, to the same terms and conditions if they work for the private company. Apparently the new jobs are at half the hourly rate paid by MI6.

Maurice Frankel, director of the Campaign for the Freedom of Information, said the cleaners would come under the 1989 Official Secrets Act, which applies to anyone working in intelligence services, security and foreign relations, no matter what job they do. The cleaners could be breaking the Act merely by telling someone they worked for MI6, he said. Terrorists might then be able to identify them and blackmail them for information.

The Foreign Office refused to comment on the claims.