France, Nov. 15 -- The burglars reportedly broke into a jewellery boutique in central Roubaix, near Lille, on Wednesday, and briefly took the jeweller and his wife hostage before making off with the valuables.

The jewels were worth "between €500,000 and €1 million, police said.

They have launched an investigation into kidnapping, organised crime and armed extorsion.

In a separate incident earlier on Wednesday, several individuals blew up a cash transfer safe belonging to Roubaix's main post office and escaped with the bag that was inside it.

It later transpired that the bag contained nothing other than more empty bags. Six people were arrested that evening.

The heists come after a gang raided the Louvre museum in Paris in...