An urgent investigation is underway in Britain after an 11-year-old boy succeeded in boarding a flight for Rome on his own without a ticket, passport or boarding pass.

In a scene straight out of the Home Alone movies, Liam Corcoran got through security checks at Manchester Airport by mingling with members of another family.

The boy, who had run away from his family, was not discovered until the Jet2.com plane was in mid air.

Passengers noticed halfway through the flight the boy was alone and alerted the cabin crew.

Manchester Airport spokesman Russel Craig says it is a security embarrassment just two days out from the London Olympics.

"Security is looking principally for any threats. He's gone through a security process," he said.

"The thing that's let us down is that he hasn't had a boarding card at that point and that's been missed.

"We are now investigating that and taking that extremely seriously."

An airport spokesman said Liam stayed onboard the plane after it landed at Rome Fiumicino Airport and returned on the same plane to Manchester, where he was met by his mother.

The Manchester Evening News said he had run away from his mother during a shopping trip at the city's Wythenshawe Civic Centre and travelled to the airport on his own.

Several staff from the airport and Jet2.com have been suspended while the investigation takes place.

The incident comes as 2 million people head to Britain for the Olympic Games, which open in London on Friday.

Security at the Games has been under the spotlight after Britain was forced to deploy an extra 4,700 troops to guard venues following a recruitment meltdown at a private security contractor.

BBC/AFP