French authorities evacuated the Saint-Lazare railway station in central Paris for a period today after receiving a bomb alert, police said.
A police spokesman said the decision was taken as a security precaution and specialised teams checked the building before declaring the all-clear.
French officials said last week the country was on heightened alert after receiving a tip-off of a planned suicide attack on the Paris metro.
Interior minister Brice Hortefeux said France was facing a real terrorism threat as it faces a backlash from al-Qaeda militants in North Africa and fears grow of an attack from home-grown cells within its borders.
A police source said the authorities had been alerted from Algeria that there was a possible threat from a female suicide bomber to the Paris metro system.
Citing unidentified security sources, French radio station RTL reported earlier in the day that the authorities had been informed of the possible bomber last Wednesday.
A spokesman for the public prosecutor said an investigation to determine the truth of the information was under way.
France has not suffered a major attack since 1995 when the Algerian Armed Islamic Group killed eight people and wounded dozens bombing a Paris metro station.
"The terrorism threat is real and as of today we have enhanced our vigilance," Mr Hortefeux told reporters without giving details of specific threats.
The authorities have visibly beefed up police and military patrolling landmarks, including the Eiffel Tower, where 2,000 people last week were evacuated after a hoax bomb threat.
Agencies