Farmers and employment agencies are preparing to launch a legal challenge against the Home Office's decision to force them to give priority to workers from Bulgaria and Romania in filling seasonal jobs picking and packing crops.

More than 15,000 temporary staff arrive each year under the Seasonal Agricultural Workers Scheme (SAWS). After the government announced in October that it would not be granting full employment rights to workers from Romania and Bulgaria, farmers were told they would be expected to fill the quota from the two countries.

'We have written to the Home Office,' said Colin Hall, director of the 50 Club of SAWS operators. 'If the response is unsatisfactory, we will look at proceeding with a judicial review.'

A Home Office spokeswoman said, 'It doesn't make sense to have in place restrictions on the economic activities of people who have the right to free movement, whilst at the same time admitting people subject to immigration controls to do the same kind of work.'

But Martin Haworth, policy director of the NFU, claims the decision was political. 'Because the government hasn't given full rights to Bulgarians and Romanians, they felt that they had to make a gesture.