The grandparents of an RAF serviceman who vanished on a night out have pledged a "five-figure reward" for information leading to his return.

Corrie McKeague, 23, from Dunfermline in Fife, was last seen in the early hours of September 24 in Bury St Edmunds, Suffolk.

He was later reported missing when he failed to turn up at his base, RAF Honington, which is ten miles from the town.

His grandparents Mary and Oliver McKeague, from Cupar in Fife, announced the reward as they said they believed his disappearance may involve a third party.

Grandfather Oliver said: "Corrie's base at RAF Honington is near two other military bases, RAF Marham to the north, and Aldershot Camp to the south, and each recently reported suspected kidnapping attempts of military servicemen.

"You could draw a near straight line on a map and connect all three. Corrie's base is right in the middle."

Grandmother Mary said: "We've pledged this reward in hopes that it will motivate someone to come forward and help us find my beautiful grandson, Corrie, who went missing the day of his stepmother's birthday.

"We're heartbroken but we're not giving up. Corrie would expect us to stay strong."

Mr McKeague, a gunner and team medic, was separated from friends while leaving the Flex nightclub on St Andrews Street South.

He was last seen in Bury St Edmunds town centre on CCTV at 3.25am wearing a light pink Ralph Lauren shirt, white jeans and brown suede Timberland boots with light soles.

The last sighting shows him walking from a shop doorway and into a horseshoe-shaped area in Brentgovel Street, with no sign of him emerging.

"The CCTV cameras show him walking in but not coming out," said Oliver McKeague. "He seems to have just vanished.

"But people don't just vanish; they leave or they get taken away.

"We think Corrie arranged to meet someone that night but we don't know who, and then got into a car and disappeared. We know he didn't just run away; he loved his fellow squaddies, his life and the career direction he had chosen.

"He was so proud the day he passed out and joined 2 Squadron RAF Regiment three years ago, and so were we."

His mother Nicola Urqhurt said she also believed another party could have been involved in her son's disappearance.

The McKeague family are asking for information from anyone who may have been in the town that evening or who may know of Corrie's whereabouts.

This can be given via the Suffolk Police incident room on 01473 782019.

A Suffolk Police spokesman said: "We are aware that Corrie's family, including his dad Martin and grandparents Mary and Oliver McKeague, are offering a reward for information to locate him.

"They, and we, are keen to gather as much information as possible to try and trace Corrie and we'd continue to urge anyone who can help to come forward."