PRESTWICK airport was at the centre of a major terror alert yesterday which saw armed police surround an Egyptian plane after it made an emergency landing with 326 passengers on board.

The drama unfolded after a hand- written note was found on board the New York-bound plane threatening to set it on fire.

After the threat was discovered, Egyptair flight 985 from Cairo touched down under fighter escort at Prestwick Airport.

The aircraft was taken to a secluded area at the southern end of the airport, away from the main terminal building, shortly after 2.30pm.

It was promptly surrounded by a heavy police presence, including armed officers, but it was several hours before passengers were led in small numbers out of the aircraft to waiting buses.

The drama began when BBC employee Nada Tafik discovered the note on board.

The journalist told BBC News: "When I went in to change my daughter about three hours into the flight, I found a note by the sink saying 'I set this plane on fire' with the seat number 46D written on it, so I immediately went to the crew and told them about it.

"It was on a hand napkin written in pencil and the pencil was actually still there so I told the crew to make sure to keep it so they can get any fingerprints off it.

"They locked the bathroom immediately so that no one could go into it.

"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.

"I said to one of the stewards, 'I don't know if this is a prank.' They said no, it can't be a prank. Either someone has a very bad sense of humour or, you know, it's very scary."

Police began disembarking passengers at about 5pm. Some of the travellers were young children but everything went calmly.

Many passengers were issued with blankets as they made the 100-metre walk to a fleet of waiting buses through heavy rain.

About one hundred police officers gathered around the plane and dog units and armed officers were at the foot of the stairs up to the aircraft.

Police Scotland confirmed that a suspicious note had been found on board, and said all passengers were to be interviewed.

As events on the ground unfolded, Detective Superintendent Alan Crawford, said: "The flight had 326 people on board, and as it approached UK and Scottish airspace there was a suspicious note found. The captain and crew took action to divert to Prestwick.

"The vast majority of passengers have now been safely removed from the plane and I fully anticipate they will all be removed very soon along with the crew.

"There may well be different nationalities involved and that could be a challenge for us but we have officers and interpreters to speak to everyone.

"The airport is still open and there is no threat to anyone else. The passengers will be taken to a safe place and speak to officers.

"There was no one removed in handcuffs and no one has been detained or arrested and we're continuing our investigation into the note that was found and its origin and motive.

"The terrorist threat has not been increased as a result of this incident today.

"Police and emergency services continually train for this type of incident and today is a demonstration of all the agencies involved and passengers are being removed safely.

"This note, whatever narrative it contained, we have to treat seriously and maintain the safety of passengers and crew.

"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.

"The captain took the decision to divert the aircraft and it's now for police to investigate where that note came from and to see if we can identify who put it within the plane and what was the circumstances leading to that."

Later, a Police Scotland spokeswoman added: "All passengers and crew have now disembarked from the aircraft.

"Officers are carrying out an extensive search of the aircraft. Passengers and crew remain in the terminal building. Interpreters are assisting officers as they begin to speak to passengers."

A team of five Red Cross volunteers were also drafted in to help look after passengers disembarking.

The specially trained volunteers were called in by South Ayrshire Council under emergency contingency procedures.

Their task was to provide emotional support to any passengers who needed it and to help look after their general welfare, a spokesman for the Red Cross said.

He added: "Many of our volunteers are specially trained in techniques of calming down people caught up in traumatic situations.

"We were called in to help by the local authority under civil contingency procedures and will remain at Prestwick Airport for as long as necessary."

Other flights into and out of Prestwick continued to operate as normal during the incident.

A statement on the airport's Twitter feed read: "No disruption to flights today, all flights are operating as normal."

The A79 was closed in both directions next to the airport between the B739 Station Road junction and the Shawfarm Road junction and reopened at about 8pm.

Last night, EgyptAir chairman Tawfiq Assi said the flight was checked by bomb disposal experts.

Assi added that he hoped it would continue on to New York City as soon as possible.