Greek authorities on Thursday stepped up efforts to prevent the spread of the deadly bird flu after new cases were confirmed.

Tests conducted in London on Thursday confirmed two more swans found dead around Thessaloniki, Greece's second largest city, had showed positive for the lethal H5N1 flu strain.

The new cases have prompted officials to extend emergency monitoring to the outskirts of Thessaloniki and threaten fines to poultry farmers who ignore health authority instructions.

Small poultry farms in Thessaloniki will be placed under the extended zone for monitoring and special monitoring sites have been set up in every area where a positive sample has been found, veterinary authorities said.

A local farmer was fined 6,000 euros (about 7,100 U.S. dollars) for ignoring the instruction to keep his birds in coops.

Source: Xinhua