Farmers are today on high alert over a possible bird flu outbreak.

They are waiting to hear from the Government whether strict restrictions will be imposed on them which could mean their chickens and other poultry being locked inside.

The Government has acknowledged there is a "higher" risk of bird flu coming to Britain after France confirmed a duck found dead there was infected with the lethal H5N1 strain of the virus.

If the virus spreads among the birds it could lead to a mass cull similar to that seen during the height of the Foot and Mouth crisis five years ago.

Farmers' leaders, worried any arrival of the virus here will put people off buying poultry and eggs, stressed the food was safe.

James Mulleneux, policy adviser for the National Farmers' Union and owner of Holbeam Wood farm near Wadhurst, said: "People are concerned about the risk to their livestock and the poultry industry.

"We have been working with the Government on contingency plans so that we are as well prepared as we possibly can be.

"If cases do emerge then there are many things that can be done to contain it such as keeping birds locked in, restricting movement of machinery and people at poultry farms and asking people to use disinfectant when leaving or going on site.

"If evidence is found, the bird will be killed and it will not be sold on to use in food.

"We need to reassure people that British birds and eggs are safe and they will remain safe. You are not going to catch bird flu from eating properly-cooked poultry and eggs."

The Department for the Environment, Food and Rural Affairs has confirmed nine swans were sent for tests over the weekend after members of the public called a helpline. None of the birds was from Sussex.

Mr Mulleneux said there was some concern about the validity of vaccination of birds.

He said: "There is not a lot of support for it. There is no perfect vaccine although there are some that could reduce the risk.

"The vaccination reduces your ability to notice any symptoms and you won't know if the virus is spreading or not.

"We believe good basic security and being vigilant is the better way forward at this stage."

A spokeswoman for Sussex Wildlife and Wetlands Trust in Arundel, which attracts dozens of species of wild birds, said the risk of migrating birds bringing the virus here was very low.

She said: "There has been no reported case of a human contracting the virus from a wild bird and the European Commission considers that avian influenza does not represent a risk to the general public.

"The disease is not in the UK at present so the risk from visiting places where there are wild birds is negligible.

"We are evaluating the risk on an on-going basis and conducting a surveillance programme in waterbirds in the UK."

Richard Barton, who owns Grassington Farm in North Chailey with 14,000 free-range chickens, said: "We are naturally concerned although we were more worried three years ago when there was an outbreak of the virus in Holland and millions of birds were killed.

"It absolutely decimated the industry over there at the time and there were very real fears it would do the same here.

"This time we are keeping an eye on what is going on and waiting to see what happens. We are as prepared as we can be."

Glyn Thomas, who runs a small farm near Cooksbridge, Lewes, said: "If bird flu did arrive I assume I would be told to keep my flock inside all the time. I would lose my free range status and have to compete against larger organisations.

"That could make things difficult. It is just a matter of waiting to see what happens."