Romania reported its first case of avian flu on Friday, but said it had not yet established whether the virus found in domestic birds in the Danube delta was harmful to humans.

The Danube delta is Europe´s largest wetlands and a major migratory area for wild birds coming from Russia, Scandinavia, Poland and Germany.

"We discovered today three cases of domestic birds which were tested positive for the avian flu in the village of Ceamurlia de Jos in the Danube delta," Agriculture Minister Gheorghe Flutur told reporters.

"There were three ducks in the yard of a peasant family."

Flutur said tests would be carried out to determine whether the flu was the deadly H5N1 strain or a less dangerous one.

"We will send the samples to Great Britain for a thorough analysis," he said.

The H5N1 avian flu virus has infected more than 100 people, killing at least 60 in Asia since late 2003 and has decimated flocks of poultry in southeast Asia.

H5N1 has been officially registered in six Russian regions in Siberia and the Urals, and has also been confirmed in Kazakhstan.

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The Romanian minister said he had imposed quarantine for three kilometres (two miles) around the site and all domestic birds would be culled to prevent the disease from spreading in the environmentally sensitive delta.

Flutur also said hunting was banned across the delta and that health authorities had dispatched medical teams to start testing for possible human cases in the area, just a few km from the Black Sea.

The head of the country´s veterinarian watchdog, Ion Agafitei, said final results of the tests were expected in a couple of days, adding: "We may find a less risky strain or a more dangerous one."

A Romanian government representative in the delta region said tests were also under way to check whether the virus had killed several swans which had been found dead nearby.

"Villagers have found several dead swans but the cause of death is still unclear," Lefter Chirica told Reuters.

In Brussels, a European Commission health spokesman said it had not yet received notification from Romania about the case. "We are seeking to establish the facts," he said.

A senior Russian health official said on Friday that an outbreak in Russia of avian flu is dying out but could make a comeback next spring.

"The outbreak is petering out, as migrant fowl leave the country," Ivan Rozhdestvensky, Russia´s deputy chief veterinarian, told a news conference. "However, we will have to see what happens when ... birds return next spring."

Experts fear the strain could mutate into a virus easily spread among humans and spark a pandemic that could kill millions of people.