NEW DELHI, Aug 1 (Reuters) - Health officials in India were monitoring four children suffering from fever on Wednesday after they had contact with dead or sick poultry in Manipur state, where authorities are fighting a bird flu outbreak in fowl.

The children have been restricted to their homes and are being visited twice a day by medical professionals, said Vineet Chawdhry, joint secretary in the ministry of health.

"We are being extra careful," Chawdhry said, adding that throat swabs and blood samples taken from the children had been sent to a federal laboratory, where tests for the H5N1 strain of bird flu will be carried out.

The children live within a 5-km (3-mile) radius of a small poultry farm where more than 130 chickens died last month from the H5N1 virus.

Health officials have checked more than 235,000 people around the affected farm since the weekend for flu symptoms, while veterinary workers have culled a similar number of birds in the remote northeastern state.

India had two major flare-ups of bird flu in its western region last year.

Manipur neighbours Myanmar, which has battled several outbreaks of bird flu in chickens this year, including one reported last week.

Globally, at least 192 people have died due to bird flu out of 319 cases since 2003, the World Health Organisation says.

The H5N1 strain remains mainly a bird virus but experts fear it may mutate into a form that passes easily between humans, triggering an influenza epidemic in which millions could die.