GETTY The UK airport where the baggage handler worked has not been revealed

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The discovery raises the alarming prospect that staff at British airports could be operating as part of a jihadi sleeper cell. A senior security source confirmed to Express.co.uk the discovery of the glove was "not the only case" and that other radicalised airport workers had been identified at more British airports. The UK airport where the baggage handler worked has not been revealed but Britain's biggest airport, Heathrow, has said it is not aware of any such incident at the west London hub.

Concerns about radicalised airport staff first came to light in France in the wake of the Paris attacks, when it emerged as many as 70 members of staff with airside clearance were stripped of their passes. At Brussels airport, which was hit by a terror attack in March, security services said at least 50 ISIS supporters were working as baggage handlers, cleaners and catering staff. Police at the Belgian airport said the workers were in possession of security badges and even had access to the cockpit of parked aircraft.

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And in August this year 300 airport staff at Heathrow had their passes suspended in a major security crackdown. Cleaners and caterers were caught up in the probe which employer Sodexo said was a precautionary measure and there were no known terrorist links. It followed news that police were investigating a scam involving airside security passes at Heathrow.

GETTY Concerns about radicalised airport staff first came to light in France

GETTY Airport staff in the US are not routinely screened

Philip Baum, a leading aviation security expert, said there were numerous examples of people working airside in the UK who had made expressions of sympathy for ISIS. He said: "You only need one bad egg - and given the tens of thousands of people who work in the aviation industry, and in some airports it's tens of thousands in one airport, it is a huge challenge. " But he added: "It is not all going to be about using screening technology. "Ultimately we need to apply common sense, we need to evaluate people, that is going to be the most useful technique that can be applied, whether you are looking at passengers or airport employees. "Airports are making a constant effort in the UK to monitor their staff and people are being encouraged to report suspicious postings that their colleagues might make on social media. "We need to recognise that in all areas of operations we have to be aware of the airside threat and it is a threat that might be due to psychological problems, such as Andreas Lubitz [who crashed a Germanwings plane into a mountainside]. "Or it might be a threat due to the nature of the industry, it is a global workforce now, or due to people's political ideologies."