Thousands of temporary nannies, nursery workers and social workers could have to pay for a new Criminal Records Bureau check each time they register with a different agency, under new Government proposals.

At the moment, agency workers are allowed to use the same background check when they move from one agency to another.

But the Government is considering changing the rules after it was decided risks to children outweighed the benefits for temporary workers.

The Recruitment and Employment Confederation fears the change will cause employers huge problems. "Nurseries will end up being understaffed as they won't be able to find temporary workers to quickly fill a gap as they will have to wait for a check," said Jean Birtles, representative for the confederation's childcare division.

Ian Johnston, director of the British Association of Social Workers, said: "It will just add to the difficulties of engaging people because of the delays in getting the necessary checks done."