A French soldier patrolling at the Louvre  museum in Paris shot and seriously injured a machete-wielding man on Friday who yelled "Allahu Akbar" ("God is greatest") as he attacked security forces, police said.

Hundreds of tourists were confined to secure areas of the world-famous art gallery in central Paris after the attacker was shot five times around 10:00 (1100 GMT) in a public area inside the complex.

Prime Minister Bernard Cazeneuve called the attack "terrorist in nature."

One soldier was "lightly injured" and has been taken to hospital, while the knifeman is in a serious condition but is still alive, security forces said.

Two backpacks carried by the assailant were checked by bomb disposal specialists at the scene and were found not to contain explosives.

The incident sparked fresh jitters in a country still reeling from a string  of terror attacks over the last two years and under a state of emergency since  November 2015.

Thousands of troops have been deployed to guard the capital, with groups of soldiers with automatic rifles a regular sight inside the Louvre and around its sculpture-filled gardens.

"It's so sad and shocking... we can't let them win, it's horrible," British tourist Gillian Simms, who was visiting Paris with her daughters, told AFP.

The huge former royal palace in the heart of the city is home to the Mona  Lisa and other renowned works of art but also a shopping area and numerous exhibition spaces.

The attacker was shot in a shopping area that leads to the museum.

"The people who were in the museum -- there were about 250 of them -- were held at a distance and confined in secure areas of the Louvre," city police chief Michel Cadot told reporters outside.

A second man whose behaviour was "suspicious" has been arrested, Cadot said, without giving further details.

France has suffered a string of attacks in recent years, beginning in January 2015 when jihadist gunmen killed journalists at the Charlie Hebdo satirical newspaper in Paris in revenge for publishing cartoons of the Prophet Mohammed.

Another attacker went on to kill shoppers in a Jewish supermarket, with a total of 17 people dead in three days of bloodshed.

Ten months later, gunmen and suicide bombers from the Islamic State jihadist group attacked bars, restaurants, a concert hall and the national stadium in Paris on November 13, 2015, killing 130 people.

And last July, a Tunisian extremist rammed a lorry through crowds celebrating Bastille Day in Nice on France's south coast, crushing 86 people to death.

In November, French police broke up an alleged jihadist terror ring which was thought to be planning to attack Paris.

Friday's incident came on the very day that Paris was submitting its formal bid dossier to host the 2014 Summer Olympics.

The Louvre was already suffering from a fall in visitor numbers after the series of attacks in France.

Over the last two years, numbers are down about two million, casting doubt on its claim to be the most visited museum in the world.

Last year, there was a 15-percent slump in visitors compared to 2015, to around 7.3 million. (AFP)