An Air France passenger has been detained as part of the investigation into the fake bomb that was planted in an Air France plane's lavatory and prompted an emergency landing.

The suspect was not identified in the statement released Monday by French authorities.

A fake explosive device placed aboard Air France Flight 463 forced the plane to make an emergency landing in Kenya en route to Paris early Sunday.

The device, left in a lavatory cabinet, was made of cardboard and paper with a timer on top, according to the Associated Press. Authorities determined there were no explosives in the device and it presented no danger to passengers or crew.

The hoax became the fourth such incident in a month.

France has been under a state of emergency since the Nov. 13 attacks in Paris that left 130 people dead and hundreds wounded. The attacks were claimed by Islamic State militants.

>>Earlier reports

A Kenyan police official says no explosives have been found yet in a suspicious device left on an Air France flight that caused the plane to be diverted to Mombasa, Kenya.

The police official, who is part of the investigation and who insisted on anonymity because he is not authorized to speak to the media, said during the flight to Paris a passenger noticed something in one of the plane's lavatories that looked like "a stopwatch mounted on a box."

The passenger reported the suspicious device to the cabin crew and pilots requested an emergency landing.

The police official said the box has been taken apart and no explosives have been found but the digital watch has not yet been analyzed.

Here's what we know now.

>>Air France flight makes emergency landing

Air France Flight 463 was heading from Mauritius to Paris when the pilots requested an emergency landing at the Moi International Airport in the Kenyan coastal city of Mombasa at 12:37 a.m. Sunday.  The plane had on board 459 passengers and 14 crew members.

>>The reason for the emergency landing

Once the plane landed and everyone had exited the plane safely, bomb experts were sent in to retrieve a suspicious device from the plane’s lavatory. A passenger had alerted a flight attendant about the item, prompting pilots to request an emergency landing.

>>Passengers remained calm

While a passenger alerted a flight attendant to the suspicious item in the lavatory, the crew did not inform the rest of the passengers about the reason for the emergency landing, only citing technical issues. According to Kenyan authorities, six passengers were questioned about the device found on the plane, though that has not been confirmed by other agencies.

>>Third bomb threat in recent weeks

According to the Associated Press, this is the third bomb threat linked to an Air France flight in recent weeks. Two other Air France flights to Paris were diverted on Nov. 18 after bomb threats were received. No bombs or suspicious devices were found.

France remains under a state of emergency since the Nov. 13 attacks in Paris that left 130 people dead and hundreds wounded.

The Associated Press contributed to this report