Businesses have expressed concern following reports that ministers are set to extend paternity leave.

Monday's newspapers suggested that the government is set to offer new fathers six months of unpaid paternity leave.

Under current arrangements fathers get two weeks paternity leave while mothers get six months.

The leave for mothers will be extended to a year in 2009.

It is thought ministers could allow fathers to take up to six months unpaid leave providing the mother forgoes an equal period from her maternity leave.

Derek Simpson, general secretary of the Amicus trade union, said that "working fathers will  be unlikely to be able to afford to take up the new right without pay".

"The birth of a new child is one of the most expensive times for a family, and  without pay, paternity leave for new fathers will remain out of reach," he said.

But the British Chambers of Commerce warned of an "administrative nightmare".

Director general David Frost said: "The issue for businesses is that plans to extend parental leave could not only be an administrative nightmare, but could leave firms without key staff for long periods of time.

"While employers want to actively support flexible working, the government must realise that extending parental leave at such an unprecedented rate will add more confusion and pressure to firms who are already struggling to compete.

"This country is becoming less competitive, the UK economic climate is worsening and the government needs to offer our firms support at this difficult time rather than burdening them with more damaging employment legislation."