Aviation minister Jim Fitzpatrick is grilled by Newnight's Jeremy Paxman
Foreign workers employed airside at UK airports do not have to undergo full mandatory criminal records checks, the BBC's Newsnight has discovered.
Since 2003, all staff have been checked against UK criminal records, but offences abroad are not covered.
The government said workers were also subject to physical security measures on a daily basis and background checks stretching back five years.
A review of security due to report in the summer would consider new measures.
After the terrorist attacks of 11 September 2001, governments across the world pledged to make airports more secure.
In the UK, the government introduced mandatory criminal records checks for all staff working airside.
The Newsnight report on airport security
But Newsnight has discovered a serious loophole in the legislation.
The list of offences covered by a Criminal Records Check is comprehensive. Anyone who has an unspent conviction for anything from theft or criminal damage to murder or terrorism would be refused a pass airside - known as the restricted zone.
But that is not true if those crimes were carried out abroad as the Criminal Records Check only covers offences which take place in the UK.
Aviation analyst Chris Yates says that leaves passengers very exposed.
If it's good enough for pilots it should be good enough for anyone else that's working airside.
Jim McAuslan, Balpa union
"We really need to ask the question, is it now necessary to restrict employment at our airports to those people for whom we can carry out the full panoply of checks?"
Around 200,000 people work airside at airports across the country. BAA would not confirm how many are foreign - though it is estimated to be in the thousands.
The sensitivity of airside security was highlighted just last year. John Parkinson, the head of aviation security at the Department of Transport, told a conference that terrorists "would have the components available airside with the help of people who work there."
And when an Al-Qaeda sympathiser, Samina Malik, who worked airside in a shop at Heathrow, was convicted of owning terrorist manuals last December, it prompted the government to launch a new review of airport security.
Al Qaeda sympathiser Samina Malik worked airside at Heathrow
That is being headed by former Home Office official, Stephen Boys Smith.
He has been taking soundings from organisations like the pilots' union, Balpa.
One of the union's key concerns is the lack of consistent checks on staff allowed airside, as its general secretary, Jim McAuslan, explained.
"I would suggest that if someone can't pass the test like that they shouldn't be employed airside at all. It seems pretty simple to us.
"If it's good enough for pilots it should be good enough for anyone else that's working airside. These checks need to be carried out on everyone."
The Department for Transport said the government would consider introducing checks on foreign criminal records as part of the transport review.
But any action to close the loophole would wait for the outcome of the inquiry.
A spokesman said the terrorist threat to aviation from airside workers is "fundamentally addressed by physical security measures, for all staff, every day".
He added: "In addition to physical security, we run a counter-terrorist check, which is far more detailed than a criminal record check, for all airside workers engaged in security roles.
"We do, in addition, require UK criminal records checks to be run on all other airside pass holders. Criminal records from other countries are of a different nature.
"Our regime includes instead the requirement for a five year background check on all airside workers."
The DfT said from 2009, new biometric ID cards would be introduced for people who work airside in the country's airports, "allowing an individual to be linked more securely to their own true identity, helping protect against crime, illegal immigration and terrorism".
'Worse than complacent'
Aviation Minister Jim Fitzpatrick has defended vetting procedures for staff.
To not do anything about it because it's inconvenient, it's a disgrace
David Davis Shadow Home Secretary
"Anybody who is able to work in a restricted zone is screened in exactly the same thorough way as any member of the public," he told Newsnight.
Under repeated questioning, Mr Fitzpatrick insisted the UK was not "complacent in the face of terrorism".
"What we are able to do is to demonstrate that anybody who is able to work in a restricted zone is screened in exactly the same thorough way as any member of the public who is travelling through our airports, and in that instance we are very confident and are safe in the knowledge that they do not pose a threat."
But not everyone shares that confidence. The Conservatives' David Davis demanded urgent action from the government.
"To not do anything about it because it's inconvenient, it's a disgrace," he said.
"They should immediately carry out security checks on all people currently working airside.
"Anybody who fails should be removed and before anybody else is employed, those security checks should be completed. And they should do that irrespective of cost and as fast as can be done - otherwise it's worse than complacent; it's reckless."
He said it was "astonishing given the history and, of course, the risk on the airside of any airport in the United Kingdom" that checks were not taking place.
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