French prosecutors have opened a counter-terrorism investigation after a man with a knife tried to force his way in to Paris' Eiffel Tower late on Saturday, a judicial source said Sunday.

The incident at the world-famous tourist site was initially treated as a criminal matter, but was later designated a counter-terrorism case because of the suspect's statements to police and his apparent radicalization, the source said.

The Eiffel Tower was evacuated at about 11:30 pm (2130 GMT) Saturday after an attempted attack by an armed man.

The man was arrested and is being held for questioning, and an investigation was opened by prosecutors.The attacker, who was apparently alone, was "very quickly overpowered and arrested" and nobody was hurt, a statement by the company that runs the Paris landmark said.

A source close to the investigation said the suspect, a French national born in Mauritania in 1998, had been in a psychiatric hospital for several months and was granted temporary permission to leave care from Aug. 4 to Aug. 6.

During questioning by police, the man stated he had wanted to carry out an attack against a soldier and was in contact with a member of Daesh terrorist group who encouraged him to act, the source said.

After pushing his way past a security guard at the entrance to the Eiffel Tower, the man approached soldiers patrolling at the site and, holding a blade, the source said.

But he complied when the soldiers told him to put down his weapon and offered no resistance when arrested, the source added.

The incident happened about half an hour before the Tower normally stops admitting visitors.

After the arrest, police at the site checked the venue and called for it to be evacuated at around 00:30, 15 minutes before the Eiffel Tower normally closes, the statement added.

The would-be intruder was wearing a Paris Saint-Germain football shirt and at the time of the incident the tower was lit up with the team colors of PSG.

A screen near the bottom of the tower displayed a message welcoming Brazilian star Neymar to the club.

France has been under a state of emergency since the November 2015 terrorist attacks on Paris restaurants, a concert venue and a sporty stadium that left 130 people dead.

Since the first wave of terror attacks in January 2015, 239 people have been killed.