"A very loud noise was heard in Paris and in the Paris region. It was not an explosion, it was a fighter jet crossing the sound barrier," Paris police said on their Twitter account, urging people to stop calling emergency phone lines.

The noise, which was heard all across the city and shook windows, rattled Parisians already on edge after a knife attack outside the former offices of the satirical weekly Charlie Hebdo last week that the government has called an act of terror.

Wednesday's incident led to confusion, with people asking on social media about a noise heard throughout the city but that left no trace of damage.

It was clearly heard during the French Open tennis tournament at Roland Garros, where star player Stan Wawrinka of Switzerland and his German opponent Dominik Koepfer paused in astonishment and worry as the noise echoed around the stadium.

Last Friday, two people were wounded in the knife attack by a man wielding a meat cleaver outside the former offices of Charlie Hebdo in central Paris.

The assault came three weeks into the Paris trial of suspected accomplices in the January 2015 attacks on Charlie Hebdo and a Jewish supermarket.

Seventeen people were killed in the three-day spree of violence, including Charlie Hebdo staff and a policewoman.

The bloodshed heralded a wave of Islamist violence in France that has so far left 258 people dead. The nation remains on high alert for terrorism risks.