"The A/H1 strain of the virus was found in samples taken from a 22-year-old woman from Hamburg. The second and third cases are a 30-year-old man and 37-year-old woman from Bavaria," a spokesman for the Robert Koch Institute in Berlin told RIA Novosti.
The seven people had been on holiday in Mexico, where over 150 recent deaths are suspected to have been caused by swine flu. Seven of the cases in Mexico have been officially confirmed.
Bavarian Health Minister Markus Soder said that about 275 passengers on the region's only direct flight from Mexico, which arrives in Munich each Wednesday, will undergo comprehensive health checks.
If a passenger develops symptoms of swine flu infection during a flight, the aircraft will be taken to an isolated location at the airport, and the passengers will be taken to medical stations for tests, he said.
Health officials in neighboring Austria have diagnosed a 28-year-old woman with the disease. Earlier this week, swine flu cases were confirmed in Spain and the U.K.
In Mexico, over 1,500 people have been hospitalized with swine flu symptoms.
Sixty-four cases of human swine flu infection have been confirmed in the United States and 13 in Canada, although there have been no fatalities. The United States has declared a public health emergency. Suspected infections have been reported in New Zealand, Israel, Brazil and Australia.
Countries around the world are taking measures to prevent a swine flu pandemic.
The World Health Organization earlier raised the level of swine flu pandemic alert from phase 3 to 4, implying a significant risk increase, one step short of a full pandemic.
