Immediate government action is being demanded as a round-the-clock watch is maintained in Southampton Docks in the fight to keep out imported food contaminated with foot-and- mouth.

The city is one of the leading import centres for animal products in the country and a team of port health officers are the first line of attack against the threat of infected cargoes entering the UK from overseas.

As the foot-and-mouth outbreak claims the lives of vast numbers of animals and threatens farmers with ruin, port health officials say they are still waiting for guidance on what they should be looking for during dockside inspections.

An example of their vigilance resulted in the detention of a container loaded with meat from Thailand, first described as clothing, which had passed illegally through the port.

The seven-strong team, which has a reputation for rigorous examination of all animal products, says Whitehall has not issued any special guidelines or assistance for inspection since the outbreak of the disease.

The officials, now considering a prosecution following the discovery of the consignment of Thai chicken, already had a tough task to perform before foot-and-mouth struck, as more than one million containers are now handled every year in the port of Southampton. Now, however, pressure has increased.

Sandra Westacott, Southamp-ton principal port health officer, said the city council had been fully supportive of the team but the department felt let down by government.

She said: "Since this epidemic started we have been given no risk assessment from the government which is very frustrating and disappointing.

"Of course we use our professional judgement, expertise and experience but we would have expected the government to have given us some guidelines.

"When you are trying to formulate a system of control you want to know what your base lines are, what are the dangers and from that make a simple model of where you should be focusing your attention.

"We are not veterinary scientists here. We don't even know whether we should be looking or shouldn't be looking, whether we should worry or not worry - we don't know.''

Initially, paperwork for the container listed the contents as "garments and bootbags", so as not to be the subject of a food product inspection, but later documents said that it was a consignment of tinned Thai chicken.

Ms Westacoott said: "The container had already left the port but we tracked it down, still in the region, and it has been brought back for further investigation.

"Thailand carries out a huge trade in chicken with China, where foot-and-mouth is endemic, and I am told chicken does not carry foot-and-mouth itself. But whether it could come in on the packaging or not, I don't know."

NFU South-East senior policy advisor William White said strict constraints on imported meat were needed.

He said: "It is astonishing that the port health authority has not been given guidance.

"Our members would say emergency powers should be in place over commercial and personal meat imports.

"We want to see tighter controls and far greater people on the ground to intercept meat and make sure the image of Britain being a soft touch for imports like tinned Thai chicken does not exist."

New Forest East MP Julian Lewis said: "Given that the outbreak has already reached devastating proportions in the UK, I suppose it's understandable that MAFF is focusing exclusively on fighting it.

"However, what the port health authority has rightly drawn attention to could well explain how this disastrous disease began in the first place."

However Southampton Test Labour MP Alan Whitehead said guidance had been issued to port health authorities.

He said: "It is possible that the guidance could do with some tightening up as to where the most likely sources are for smuggled meat from foot-and-mouth countries.

"I have certainly taken this up and checked that guidance has been sent out.

"If necessary, it could be made more explicit or clearer in the form of a compendium of risk."