Experts are still trying to determine the source of an outbreak of bird flu at a Suffolk farm as a cull of thousands of turkeys nears its end.

Government vets said nearly 160,000 turkeys will have been gassed to contain the outbreak at the Bernard Matthews site near Lowestoft. They say the H5N1 strain was similar to a case in geese in Hungary in January.

The government’s crisis management committee Cobra is to meet for updates on efforts to contain the disease. There are industry concerns that poultry may hit sales, and Japan has suspended imports of UK birds.

That temporary move is a standard procedure carried out by Japanese authorities after a country has reported a bird flu outbreak. Bernard Matthews will be entitled to receive compensation under the Animal Health Act for all healthy birds slaughtered to control diseases.

The Department for the Environment, Food and Rural Affairs (Defra) said the firm could claim under the Animal Health Act 1981 the value of each bird just before slaughter as well as that of any eggs and property removed and destroyed

Investigations are continuing into how the disease, identified as the “highly pathogenic” Asian strain of the H5N1 bird flu virus, entered the poultry flock.

There are suggestions the most likely way for the virus to have been spread by wild birds.

However, migration does not take place at this time of year and there were no indications of an EU outbreak from monitoring programmes. The experts acknowledge it may be impossible to trace the exact cause of the outbreak, our correspondent said.

The cull at the farm at Holton, about 27km south-west of Lowestoft were expected to be completed by yesterday morning. Fourteen sealed lorries containing the bird carcasses have been travelling to a rendering plant in Cheddleton, Staffordshire, for incineration.

The first turkeys died at the site last week and government vets were called in on Thursday after a vet for the Bernard Matthews company concluded the disease was “unidentifiable”. The authorities have denied their response was slow.

Rural Affairs Minister Ben Bradshaw told reporters: “I’m satisfied that everyone has moved as quickly as they possibly could have.” Fred Landeg, the government’s deputy chief vet, said that although the company vet was called out on Tuesday, turkeys only began to die in significant numbers two days later, suggesting avian flu might be the cause.

A biosecurity zone has been set up around the farm and poultry owners in the restricted area have been told to keep their flocks isolated from wild birds.

A three-kilometre protection zone and a 10km surveillance zone also remain in place around the farm site. A much wider restricted zone covering 2,090 sq km is bordered by the A140 to the west and the A47 to the north and almost to Felixstowe in the south. Health experts have been quick to quell fears the virus found in Suffolk could be passed on to humans.

The avian flu virus has so far killed 164 people worldwide – mainly in south-east Asia – since 2003. So far, all those who contracted the virus had come into close contact with infected birds. The virus has so far been detected in only one shed out of 22 at the site, and 100 of the 2,000 staff who work at the Holton farm have been given the Tamiflu anti-viral drug.

None of the affected birds had entered the food chain and there was no risk to public health.

United Nations co-ordinator for bird flu, David Nabarro, has said farmers will have to get used to the presence of the disease in the UK as it is “going to be in bird populations for several years to come”.

<B>Outbreak predictable</B>

United Nations officials said they were not surprised by the outbreak of H5N1 avian influenza and said they have been expecting the virus to spread during the colder winter months, much as it

did last year.The Department for the Environment, Food and Rural Affairs or Defra issued a statement on Sunday saying it appeared the virus had been confined to the Bernard Matthews farm near the town of Lowestoft. Dr. David Nabarro, the United Nations bird flu envoy, said Europe should be ready for more outbreaks. “t’s a cause for concern but at the same time because the response is right I think the concern should be quite limited,” Nabarro said in an interview in Jakarta.

He said wild birds, which can carry the virus without becoming sick, probably infected  the turkeys.