European Union authorities launched an alert Sunday to find airline passengers who travelled on flights with a Thai man who tried to smuggle two bird flu-infected Asian eagles into Belgium.

Belgium´s public health ministry said it was trying to find the Thai man himself following confirmation Saturday that the two Mountain Hawk Eagles were infected with avian influenza.

The EU´s executive arm said it had received a request from Belgian authorities also "to assist them in their search for flight passengers of different nationalities who might have been exposed to the flu virus".

"Although the risk of transmission from the animals to humans is limited, it cannot be excluded since the birds travelled in the passenger cabin in hand luggage," the European Commission said in a statement.

The commission said it was anxious to prevent any introduction into Europe of the deadly virus, which has hit six Asian nations killing at least 30 people so far.

The Thai man was apprehended by customs officers at Brussels airport when the eagles were discovered in his bags last Monday, live and wrapped up in plastic tubing. But he was apparently then released.

The European Commission said travellers on the man´s flights should see their doctors as a precaution if they start showing flu-like symptoms including nausea, fever and colds.

The man flew on flight BR0061 of Taiwanese airline EVA from Bangkok to Vienna late Sunday, arriving early Monday, and then Austrian Airlines flight OS351 to Brussels on Monday morning.

"Although passengers?lists are available for the two flights concerned, address details of the passengers are not known," the commission said.

But it added: "The birds never left the quarantine installations at Brussels airport and did not pose any threat to the European poultry flock."

Customs officers and scientists who came into contact with the birds of prey are being given preventive anti-viral treatment, news reports said.

The eagles have been destroyed, as have two parrots that were being kept at the same quarantine centre, the Belga news agency said.