French police shot dead a man wielding a meat cleaver after he tried to enter a police station on Thursday, the anniversary of militant attacks in Paris, shouting "Allahu akbar" (God is Greatest) and wearing what turned out to be a fake suicide belt.

The Paris prosecutor said the man was also carrying a mobile phone and a sheet of paper bearing the Islamic State flag and a claim of responsibility by the militant group written in Arabic.

According to a judicial source, Ali Sallah, was a Moroccan born in 1995 in Casablanca. He was homeless and known to police for theft in 2012 in the Var region of southern France.

French Justice Minister Christiane Taubira told French television i-Tele that from what was known so far, the man had no known links to violent Islamist radicalism.

She suggested he might have been mentally unstable.

Thursday is the first anniversary of deadly Islamist attacks on the Charlie Hebdo satirical magazine in the French capital and Sallah's attack came just minutes after President Francois Hollande had given a commemoration speech elsewhere in Paris.

Security concerns intensified further in France in November when 130 people were killed in shootings and suicide bombings targeting a Paris music hall, bars, restaurants and a stadium.

Those attacks were claimed by Islamic State, the militant group that controls swathes of Iraq and Syria. Several of the militants involved were, like the Hebdo killers, French-born.

In his statement, Paris Prosecutor Francois Molins said a terrorism inquiry had been opened into Thursday's attack.

"(The man) shouted 'Allahu akbar' and had wires protruding from his clothes. That's why the police officer opened fire," a police official said.

French Interior Ministry spokesman Pierre-Henry Brandet later said the suicide belt the man was wearing was fake.

Journalist Anna Polonyi, who could see the outside of the police station from the window of her flat, posted photos on social media that showed what appeared to be a bomb-disposal robot beside the body of the man, who was wearing jeans and a gray coat.

Polonyi told Reuters that her sister, in the flat with her, had seen the incident. She said the police shouted at the man and that they shot him as he was running towards them.

In his commemoration speech, Hollande promised to equip police better to prevent further militant attacks. He also defended draconian security measures implemented since November that his Socialist government had once shunned.

Last year's attacks have boosted the popularity of the far-right, anti-immigrant National Front party ahead of a presidential election due in 2017.

"Terrorism has not stopped posing a threat to our country," Hollande said.

Since the November attacks, Paris has increased its efforts to strike militants in Syria and Iraq, becoming the second largest contributor to the U.S.-led coalition against Islamic State.

Security measures at home have included a three-month state of emergency during which the police have launched hundreds of raids on homes, mosques, restaurants and hotels.

Separately on Thursday, a French court sentenced a French-born Islamist militant in absentia to 15 years in jail for his role in recruiting militants to fight for the group in Syria in 2013.

The whereabouts of Salim Benghalem, 35, who is believed to have had links to the perpetrators of both series of Paris attacks, remain unknown. He is suspected of being an Islamic State executioner and of having led a group of French-speaking jihadis in Raqqa, Syria.

The French court sentenced six other defendants at Thursday's hearing to jail terms of between six and nine years for being part of the recruitment network.

It was the first such court case involving militant Islamists in France since the November killings.