Two of Paris' biggest and most famous tourist attractions were cleared and closed on Saturday in response to attack threats.

Around 15,000 visitors were requested to leave the Louvre in central Paris after the museum "received a written message stating that there was a risk to the museum and its visitors," a museum spokeswoman told French news agency AFP.

She didn't initially elaborate on the precise nature of the threat but French broadcaster BFMTV cited police sources who said the museum had received "bomb threats."

Alarms rang out through the museum and in the underground shopping center beneath its signature pyramid, with some visitors hurrying to the exits and others reportedly taking photographs.

Later in the afternoon, the Palace of Versailles on the outskirts of Paris was also evacuated after security services received an anonymous bomb threat.

France on high alert

The evacuations come with France on its highest security alert after a teacher was stabbed to death in a knife attack at a high school in the northern city of Arras on Friday.

Authorities say a former student suspected of Islamic radicalization killed a teacher and wounded three other people before being captured. 

On Saturday, amid fears that the escalating conflict between Israel and Hamas could lead to violence in foreign capitals, France announced it would deploy up to 7,000 soldiers as part of Operation Sentinelle.

Sentinelle is a French military operation involving the deployment of soldiers, police and gendarmes set up in the aftermath of January 2015 attacks to protect parts of the country deemed sensitive from terrorism.

The Louvre, home to masterpieces such as the Mona Lisa, welcomes between 30,000 and 40,000 visitors per day.

Roughly 15 million people visit the Palace of Versailles and its gardens every year, making it one of the most popular tourist attractions in the world.

mf/msh (AFP, dpa)