Priceless jewels have been stolen from the Louvre Museum in Paris.

Paris police say they are searching for a group of thieves.

French Interior Minister Laurent Nunez said it took only minutes for the masked suspects to carry out the robbery, which took place on Sunday morning, while the museum was open to visitors.

The robbers reportedly used a ladder from a car to reach the museum's first-floor window, broke the jewelry off its display, and escaped on a small motorcycle.

The jewels stolen by the robbers were used by the French royal family. Authorities said nine pieces of jewelry were stolen.

They also said a crown belonging to Napoleon III was found lying in the area.

The Paris prosecutor said the thieves used a battery-powered cutter to break into the building.

Four people were involved in the robbery, and two of them threatened security guards after entering the building.

A ladder truck was reportedly used to climb up to the first-floor window of the building.

Police have banned visitors from entering one of the world's most visited museums and closed it to research.