The Government was today appealing directly to farmers to back its plans for a limited campaign of vaccinations to save hundreds of thousands of cattle from foot-and-mouth disease.

An advert in the Farmers' Weekly magazine spelt out the thinking behind plans for inoculation of cattle in Cumbria, and possibly Devon, before the animals are put out to pasture from the barns where they have spent the winter.

The Ministry of Agriculture has published on its website Government scientists' answers to a list of 50 questions about vaccination posed by the National Farmers' Union.

Prospects yesterday seemed to be fading of the vaccination campaign beginning before the cows are moved into fields, where they face the risk of possible exposure to the foot-and-mouth infection.

Following meetings with chief vet Jim Scudamore and chief scientist Professor David King, NFU leader Ben Gill said that several "major issues" needed to be settled before he could offer his support for the jabs.

The process of clearing up his members' concerns could take as long as two weeks, he warned.

Further discussions between Mr Gill and the Government scientists were due to take place today.

After weeks of playing down the value of vaccination, Downing Street announced on Tuesday that it "accepted in principle" the argument for selective jabs in the worst-hit areas.

But today's advert made it clear that the Government was not planning to push the policy through against opposition from farmers.