140 people were onboard as the drama unfolded

On its return to Glasgow all the passengers were safely taken off the plane and into the terminal building as engineers began to empty the hold to search for the source of the smoke.

Strathclyde Fire Brigade said it was called to the airport after receiving a report of a "small fire in the luggage hold".

A spokesman said 20 firefighters were on standby for the emergency landing.

Inflatable chutes

A Scottish Airports spokeswoman said: "Glasgow Airport was closed for half-an-hour to allow the plane to perform an emergency landing.

"Once it landed the airport's fire service and local emergency services were deployed to the scene and inflatable chutes were used to get the passengers off."

Continental Airlines later said there was no fire on board flight number CO17, but a statement confirmed a warning light appeared indicating "a possible overheating" in the cargo hold.

The statement said: "As a precaution, the captain decided to return to Glasgow and activated the cargo hold extinguishers in flight.

No fire

"Upon landing at 1.36pm the local emergency services opened the cargo hold and believed that the residue from the fire extinguishers could have been smoke.

"As a precaution they recommended to the crew to carry out an emergency evacuation of the aircraft."

The statement added: "Subsequent examination indicates that there was no fire."

Continental said 134 passengers and eight crew were on board.

They are being offered overnight accommodation and will fly again on Friday.