A vet involved in the bird flu outbreak in Suffolk is in hospital with a mild respiratory illness, the Health Protection Agency said.

The vet , who was not named but is believed to be in his late 50s, is being tested for H5N1, the potentially lethal form of avian flu, in an isolation ward at Nottingham City Hospital.

The HPA stressed last night that the tests were precautionary, and he would be tested for avian flu as part of many tests. Results are expected today.

A HPA spokesman said: "It is highly unlikely the worker has been exposed to H5N1 because of the strict precautionary measures followed. The individual had not been pre-exposed and was wearing full protective clothing. As a precaution we are testing for H5N1."

The government vet was reported to have spent two days investigating the H5N1 outbreak in Holton, Suffolk, before returning home to Nottingham on Monday. Yesterday, he began feeling slightly unwell.

A spokesman for the Department of Environment, Food and Rural Affairs (Defra) said that all employees of the State Veterinary Service are issued with, and are trained to wear, respiratory protective equipment and protective eyewear. "They are also face-fit tested to ensure they receive maximum protection," he said.

Professor John McCauley, a bird flu specialist with the MRC National Institute of Medical Research, urged the public not to panic. He said the priority was to establish whether or not the vet had H5N1 but, even if that is so, with swift treatment the situation can be contained. "The infecting of one person is not a critical event," he said. "It is if the person spreads it to someone and then on to someone else ­ that's when it becomes critical."

In 2003, a Dutch vet died after handling infected birds, although he was infected by the H7N7 strain, Professor McCauley said. "The message is, there is always the risk of someone who has been involved becoming infected, it has certainly happened in the past." He added: "It is bad luck. I hope the person is OK. I hope it is not flu, and if it is, I hope the Tamiflu works."

A spokeswoman for the Strategic Health Authority in East Anglia said: " All we can do is to wait and see whether or not it is a confirmed case," she said.

The H5N1 virus, which has killed dozens of people who work closely with poultry in Asia since 2003, has only passed from human to human in a possible four cases.

The Bernard Matthews food company, which runs the poultry farm where 160,000 turkeys have had to be culled, has defended its handling of the outbreak. The commercial director, Bart Dalla Mura, said the company had no idea the turkeys were suffering from bird flu until Defra told it on Friday. "We heard the birds weren't well on Wednesday, the mortality increased a bit more on Thursday and that is when our vet said: 'I'm going to contact the next stage of the line.' The last thing we thought is that they had avian flu," he said.

He said biosecurity at the Holton site, which employs 1,000 workers, was "good or better than required". He said the infection was confined to one out of 22 sheds and there was no evidence it had spread. A 3km (1.9 mile) protection zone is in place around the farm, which will reopen once Defra gives it the all clear.

EU vets said yesterday the outbreak is unlikely to be linked to one in Hungary last month.

The EU also said bans on UK poultry imports imposed by Russia and Japan were unnecessary.