Airports across France were evacuated on Wednesday after emailed "threats of attack", a police source told AFP, the latest in a series of similar alerts.

The evacuations at Lille, Lyon, Nantes, Nice, Toulouse and Beauvais airport near Paris would allow authorities to "clear up any doubts" whether the threats are real, the source said.

A spokeswoman for Strasbourg airport in eastern France also said the site was being evacuated after a "threatening email".

The Palace of Versailles, a major tourist attraction outside Paris, was evacuated for the third time since Saturday for bomb disposal teams to check the site.

France is on high alert following Hamas's October 7 attack on Israel and Friday's fatal stabbing of a teacher in the northern city of Arras by a man claiming allegiance to the Islamic State group.

A second police source said that Nice, Lyon and Lille airports had resumed normal activity around midday.

A spokesman for France's DGAC aviation authority confirmed evacuations over bomb warnings only at Lille, Lyon, Toulouse and Beauvais, and was unable to give further details immediately.

The DGAC's online dashboard showed significant delays at Lille, Lyon and Toulouse.

A post on Nice airport's X (formerly Twitter) account said that "following an abandoned baggage item... a security perimeter was set up to allow the usual checks".

"The situation has now returned to normal," it added.

Airport authorities at Lyon's Bron airport also said the all-clear had been given.

In Lille, an airport spokeswoman said three flights had been diverted, while a post on its X account said security forces were on the scene.

Some passengers posting on social media were apparently in the dark about why they were being ushered out of airports.