The knife-wielding attacker who was shot by a French soldier outside the Louvre museum has been declared fit to be interviewed after his condition improved and placed in formal detention, the Paris prosecutor's office said on Saturday.

The 29-year-old Egyptian, identified as Abdullah Reda al-Hamamy, was shot several times on Friday after he set upon soldiers with a pair of machetes in what French President Francois Hollande described as a terrorist attack.

"His life is no longer in danger," an official at the prosecutor's office said.

One soldier was injured in the incident near the entrance to the museum, which went into lockdown and closed for the rest of the day, reopening on Saturday. The attacker was carrying a backpack that contained paint spray cans but no explosives, police said.

READ: French soldier shoots, wounds machete-wielding attacker at Paris Louvre

READ: Louvre attack suspect identified as 29-year-old Abdullah Reda - Egypt sources