(Recasts, adds details)

By Dave Graham

BERLIN, April 29 (Reuters) - Germany confirmed its first three cases of swine flu on Wednesday, marking the arrival of the virus in the heart of continental Europe.

The Robert Koch Institute, a federal agency for infectious diseases, said it found swine flu in a man and a woman in their late 30s in Bavaria, and a 22-year-old woman in Hamburg.

Authorities said all three of those infected with the new H1N1 virus had recently returned from Mexico.

Spain and Britain have both identified two cases of the virus each, but no infections have yet been confirmed in central or eastern Europe, according to latest reports.

Polish authorities said they were waiting for test results from two suspected cases.

German officials said the first man identified in Bavaria was from Mallersdorf, with the woman, 37, from Kulmbach further north. Doctors in Regensburg confirmed the infections.

Medical authorities are known to be investigating five other suspected incidences of swine flu in Germany. These include a further Bavarian case, and another three in the state of North Rhine-Westphalia.

The fifth suspected case involves a married couple from the northern city of Braunschweig who had recently returned from New York. The wife has already tested negative for the virus.

Pig futures prices in Germany fell slightly on Tuesday due to concerns over the spread of swine flu from Mexico.

The new H1N1 virus has been confirmed around the world but Mexico remains the only country with deaths -- 159 by the government's estimate -- and the epicentre of the outbreak. (Additional reporting by Petra Jasper and Karolina Slowikowska) (Editing by Richard Hubbard)

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