A passenger plane en route from Warsaw to Egypt made an emergency landing in the Black Sea city of Burgas early on Thursday following a bomb threat, officials said.

All 161 passengers and crew were evacuated by Bulgarian special forces, who found no explosives in an initial sweep of the plane, a Burgas airport spokeswoman said, adding that the airport remained closed.

A passenger identified as Agata Pinuszewska told Polish broadcaster TVN24 that the plane diverted to Burgas after another passenger shouted that he had a bomb.

"After landing the plane stayed about an hour (on the tarmac)... Anti-terrorist police entered the plane and started to shout to this man "where do you have this bomb?". Then we were walked out of the plane," she said.

The Airbus A320-232, operated by charter firm Small Planet Airlines Poland, was en route to the Red Sea resort of Hurghada.

It was towed to a remote location at Burgas airport, where it was undergoing a second check by Bulgarian special forces, a police spokeswoman said.

She said a passenger who later admitted having consumed alcohol had alerted crew about a possible bomb on board.

Bulgaria had tightened controls at its borders and airports in recent days, she added, following Friday's militant attacks in Paris in which 129 people died.

Jakub Flasinski, vice consul at the Polish embassy in Sofia embassy, said authorities were awaiting final confirmation that the plane was safe.

The airline would decide whether the flight continued its route or headed back to Warsaw, the Burgas mayor told reporters.