Flights were delayed in 11 states when a plastic bottle disguised as an explosive was found in a rest room at a major air traffic control center.

It was a hoax - the ominous liquid in the device was mostly water and sugar. But the FBI is not fooling around."This is a very serious matter that deserves a full criminal investigation," said FBI spokesman Jeff Lanza. "Someone needs to face the music on this one."

Lanza said the device, found on a shelf in a first-floor men's room at the Kansas City Air Route Traffic Control Center on Wednesday, looked like a bomb. The clear plastic bottle had a disposable cup on top, with a cigarette sticking out like a fuse. It contained a brownish-yellow fluid.

Controllers rerouted about 200 flights and temporarily grounded flights at airports in the region. About 80 aircraft were delayed on the ground for up to 44 minutes.