French authorities on Tuesday arrested four more people in the probe into last month's spectacular daylight theft of imperial jewels from the Louvre museum, the Paris prosecutor said.

"They are two men aged 38 and 39, and two women aged 31 and 40, all from the Paris region," Laure Beccuau said, after arresting and charging four others over the October 19 heist.

Last month, a four-strong gang raided the Louvre, the world's most-visited art museum, in broad daylight, taking just seven minutes to steal jewellery worth an estimated $102 million before fleeing on scooters.

The thieves parked a moving truck with a ladder below the museum's Apollo Gallery housing the French crown jewels, ascended in a bucket, broke a window and used angle grinders to cut into glass display booths containing the treasures.

The daylight robbery raised doubts over the credibility of the world's most-visited museum as a guardian for its myriad works.

So far, no trace has been found of the stolen jewels.

The four already charged over the theft include three men and a woman.

One of those men, a 37-year-old, was in a couple with the woman and they have children, Beccuau said earlier this month.

The thieves dropped a diamond- and emerald-studded crown that once belonged to Empress Eugenie, the wife of Napoleon III, as they escaped.

But they made off with eight other items of jewellery including an emerald-and-diamond necklace that Napoleon I gave his second wife, Empress Marie-Louise.