Four more people from the Paris region have been taken into custody as investigators widen their probe into the October theft of high-value jewellery at the Louvre.
Authorities said the detainees — two men aged 38 and 39 and two women aged 31 and 40 — were arrested on Tuesday.
Investigators believe one of them may be the remaining member of the four-person team that carried out the daylight raid.
Police now have up to 96 hours to question the suspects.
So far none of the pieces, valued at about €88 million, have been recovered.
Earlier in the inquiry four other people were charged, including three men and a woman.
A 38-year-old woman faces charges of complicity in organised theft and criminal conspiracy, while a 37-year-old man has been charged with theft and criminal conspiracy; both have denied involvement.
Two additional men were charged in October after investigators said they had partially acknowledged a role.
Prosecutors say the thieves used a stolen vehicle-mounted lift to reach a balcony above the Galerie d'Apollon near the Seine, then cut open display cases with a disc cutter.
The group was inside the gallery for only about four minutes, escaped initially on scooters shortly before 09:40 and then transferred to cars.
One crown was dropped during the getaway, but eight items were taken, among them an emerald-and-diamond necklace once given by Napoleon I to Empress Marie-Louise.
Officials have described the suspects as low-level criminals rather than members of a sophisticated organised crime ring.
The incident prompted scrutiny of the museum's security after it emerged the only camera covering the gallery was not pointed at the balcony used in the break-in.
Louvre president Laurence des Cars has acknowledged institutional failings while urging greater investment in protection.
In response to the theft, security measures across France's cultural sites have been strengthened and some of the museum's most valuable jewels moved to the Bank of France.
The investigation is ongoing as police continue to search for the missing pieces and build their case against those arrested.
