An unarmed man is thought to have stolen tens of thousands of pounds in cash from a security van at Gatwick airport today.

The raider struck at about 7.30am as a blue Brinks Ltd security van made routine collections and deliveries to shops at the South Terminal.

The van was parked in the South Terminal service tunnel when the lone man attacked.

One member of the two-man crew was on his own in the vehicle at the time, said Detective Chief Inspector Mike Alderson.

The raider punched the crew member in the face and seized foreign banknotes of 12 different currencies from the back of the van, then fled. Initial reports he was carrying a gun have been denied.

Mr Alderson said: "Early indications are there was one perpetrator.

"One person was away from the van. While he was away the van was attacked and a significant amount of money was taken."

He did not believe a weapon had been used.

The victim, a man in his late 30s or early 40s, was taken to East Surrey Hospital at Redhill and treated for a suspected broken nose.

A Sussex Police spokesman refused to confirm the exact amount stolen but said: "We are not talking about millions."

Mr Alderson stressed that the incident did not happen in a security-controlled zone within the airport.

He added: "Gatwick is a counter-terrorist airport and this type of incident is highly unusual."

Mr Alderson said police were examining security camera footage and speaking to people who witnessed the incident, which lasted a matter of minutes.

The suspect was white and in his 30s with a goatee beard. He wore a light blue shirt, dark blue trousers and a helmet.

Mr Alderson said the victim was being interviewed and would be quizzed about the possibility the clothes the suspect was wearing could have been mistaken for a security uniform.

He said: "We are investigating the possibility the offender was posing as a security guard."

Gatwick police say there are no obvious links with recent robberies at Heathrow.

An airport spokesman said the robbery and subsequent police operation had "a minimal impact" on flights.