Twenty people in France are suspected to be infected with swine flu virus so far and are put under observation, French health authorities said Tuesday.

A total of 107 French people have reported symptoms of flu after returning from Mexico since April 25, and 30 of them were listed as possible swine flu cases after the first round of medical tests, Francoise Weber, head of French Institute for Public Health Surveillance (INVS), told a press conference here.

Ten people were ruled out of infection after further tests, and at present 20 others were still going through medical checkups. The suspected cases are currently put on isolation.

The health official expected more people to be going through tests for possible swine flu infections, with more French returning from Mexico, where nearly 160 people have died after contracting the virus.

In a statement published on its website Tuesday, the French Foreign Ministry strongly advised its nationals not to travel to Mexico because of the deadly flu epidemic that started there.

French President Nicolas Sarkozy, who is now on a visit to Spain, on Tuesday called on French citizens to stay on alert, saying that the French government has been closely following the situation and would inform the public of all related developments.

(Xinhua News Agency April 29, 2009)