Three of the four suspected cases of swine flu in France were given the all-clear late on Sunday, authorities said.

The test result for a fourth one was expected to be announced on Monday.

Earlier on Sunday, France had reported four suspected cases of the swine flu among travelers returning from Mexico.

The French government was monitoring closely the development of the epidemic and has taken a series of measures, including remaining in close touch with the World Health Organization (WHO) and other European governments and keeping provincial authorities informed of the latest developments, Health Minister Roselyne Bachelot-Narquin told a press conference.

The government has also issued recommendations for tourists and reminded medical staff to be on alert.

A crisis center has been set up, while the Foreign Ministry has opened a hot line for French nationals living abroad.

There was still the possibility of some people having been infected with the virus and back to France or elsewhere in Europe, General Health Director Didier Houssin told local media.

He said the health authorities will do their best to ensure a swift diagnosis of all suspected cases.

France has never imported pigs or pork from Mexico, said a spokesperson at the Agricultural Ministry, adding that no swine H1N1 virus had been found in pigs raised in France.