Egypt Air plane
Egypt Air planeReuters

An Egypt Air plane from Cairo bound for New York made an emergency landing in Scotland on Saturday, after a passenger discovered a letter threatening the aircraft.

Authorities are working to ascertain who wrote the note found in the aircraft’s lavatory, which forced Flight 985 -- carrying around 300 passengers en route to John F. Kennedy Airport  -- to make an emergency landing at Glasgow's Prestwick Airport.

There have thus far been no arrests, police said late Saturday.

The place, escorted by British Typhoon fighter jets, stayed at Glasgow's Prestwick Airport for several hours before passengers were able to disembark, at which point officers searched the aircraft.

The BBC said one of its producers, Nada Tawfik, had discovered the note, written in pencil on a napkin, with the words "I'll set this plane on fire" and what appeared to be a seat number written on it.

She said that after discovering the note by the lavatory sink, she alerted cabin crew who then locked the toilet.

"It almost looked like a child's handwriting or someone who has very sloppy handwriting, but it was very alarming especially these days when everyone is so concerned about safety on flights" she told the BBC, saying she told the stewardesses she wasn't sure if the note was a prank or not. "Either someone has a very bad sense of humor or, you know, it's very scary."

Authorities are still investigating where the note came from, who put it on the plane and under what circumstances.

"This note, whatever narrative it contained, we have to treat it seriously and maintain the safety of passengers and crew," Crawford said. "Whether it is a prank or not this will be investigated thoroughly to establish the circumstances. We could never write something off as a prank without investigating."

Arrangements for onward travel will be made once all passengers have been interviewed, police said, according to reports.