Two women have been arrested in connection with an alleged plot to sell airside passes at London's Heathrow airport. The Metropolitan Police said the women, believed to be workers at the UK biggest airport, have been held on suspicion of fraud and money laundering allegations.

Airside security passes are used to gain entry to some of the most secure areas of an airport. Sky News reports that allegations of the sale of airside passes would raise major security and terrorism concerns. The passes are issued to around 70,000 airport employers.

Kevin Hurley, former head of counter-terrorism at the City of London Police, said: "It could be used to get close up to some of the high-value cargo areas and of course we have already had the Brinks Mat saga here once before.

"Billions go through this airport every year. But the real issue is the threat in terms of airport security; this is a potential serious breach for Heathrow Airport."

A Metropolitan Police spokesperson said: "We can confirm that officers from the Met's Aviation Policing Command are investigating an allegation of fraud, reported to them on 28 July 2016. Detectives arrested two women from Surrey, aged 24 and 20, on suspicion of fraud and money laundering on Wednesday, 3 August.

"They have been arrested in relation to an allegation that money has been fraudulently taken from a bank account. Other matters have come to light during the enquiries and form part of the ongoing investigation.

"The women were taken into custody at a west London police station and have subsquently been bailed to return to the police station in late November. Detectives searched a residential address in Surrey under the Police And Criminal Evidence Act."

Last year, airport security at Sharm el-Sheikh in Egypt came under huge scrutiny after Kogalymavia Airlines flight 7K9268 crashed over northern Sinai, resulting in the deaths of 224 people, mainly Russian tourists.

The Department for Transport said: "We are aware of this issue. Safety and security of passengers is our priority. We keep aviation security under constant review, but as this matter is the subject of an ongoing police investigation we are unable to comment further at this time."

A Heathrow spokesperson said: "We can't comment on the specifics of an ongoing police investigation. Our top priority is the security and safety of our passengers and colleagues and we have taken appropriate action until the investigation is completed."