NEW DELHI, Aug 2 (Reuters) - India said on Thursday it had contained an outbreak of bird flu in the remote northeastern state of Manipur after slaughtering nearly 300,00 birds.

However, state authorities were monitoring the health of four children with fever who had handled dead or sick fowl, and have sent their blood and throat swab samples for testing.

The flare-up of the H5N1 virus in chickens in a small poultry farm near Manipur"e;s capital, Imphal, was the country"e;s first in a year, prompting authorities to kill all poultry and destroy eggs within a 5-km (3-mile) radius.

"The outbreak appears to have been localised," said Upma Chawdhry, joint secretary in the federal Animal Husbandry Department, adding that teams were sanitising poultry farms, including destroying egg trays and disinfecting coops.

Manipur borders Myanmar, which reported two outbreaks of bird flu in chickens in July alone.

Myanmar is seen as a potential blackhole in the global fight against avian influenza, given its rudimentary health infrastructure and its secretive regime.

India had two major outbreaks last year in its western region -- both of which were successfully contained.

Officials said they were also investigating the deaths of about 120 chickens in Mizoram state, which neighbours Manipur.

Chawdhry said the deaths seemed to be due to the fowl pox viral disease but added that authorities were not any taking chances as the dead chickens were just 10 km from the Myanmar border.

"This situation is under careful watch," she said.

Avian influenza of the H5N1 strain has killed at least 192 people out of 319 cases, and led to millions of chickens and ducks being slaughtered in dozens of nations.