Could bombs be smuggled onto planes in smartphones? Passengers flying to US to have their mobiles screened as new terror alert creates travel chaos for holidaymakers

Smartphones are to be subject to extra checks at airport security amid fears terrorists could be converting them into 'stealth bombs'.

American officials have called on UK terminals to bring in stricter checks on electronic devices after warning Islamic extremists are making explosives which are undetectable to airport scanners.

US officials have identified iPhones and Samsung Galaxy models as the biggest concern as queues snaked around some of the UK's busiest airports today.

Queues at Manchester Airport this morning, the day after new security checks were brought in to search for so-called 'stealth bombs' which are feared to be undetectable to airport scanners

Passengers joined queues starting outside Manchester airport today, with many complaining of delays

Long lines of people have already built up at airports around Britain in the first two days of the stricter controls, with passengers taking to Twitter to vent their anger.

Ian Moreno-Melgar, who was trying to get to Belfast this morning for a wedding, tweeted: '“Airports operating normally”. Queuing in the car park for security isn’t normal.'

He added: '[Manchester] staff obviously under a lot of pressure,but no priority or care for passengers potentially missing flight because of security.

'Genuinely awful service from the usually reliable airport today. 90mins in security, no communication about changes to bag searches.'

Chantel McGregor added: 'Ahhhhh bless Manchester airport baggage check, we're finally half way down the queue which started OUTSIDE!'

Another passenger said: 'This is the absolute worst security queue I have ever been in. It's like wading through treacle.'

Last night, Matteo Pescarin posted a photo of queues filling a terminal at Gatwick airport's North Terminal as hundreds of passengers waited to go through security.

Other passengers took the delays with good humour, with David Silvester tweeting: 'Just had my croissants x-rayed and then inspected... #Airportsecurity'

Cameron: Security precautions are necessary

There were queues at passport controls at Gatwick airport last night after tougher checks were brought in

Passengers wait at Heathrow Airport this morning as security staff carry out more stringent security checks

Queues to get to security at Glasgow Airport, where passengers complained of waiting times today

At Glasgow Airport, passengers said they noticed longer waiting times from previous journeys.

Norma Decent, 59, from Stranraer, said: 'It seems absolutely ridiculous to me. You had to queue to get through the first gate and then queue again to put your bags through security.

'I understand why they're doing it, but it all seems a little excessive to me.'

Laura Macpherson, 42, from Paisley, who was travelling with her two children, said: 'Normally it only takes about five or 10 minutes, but I think we were queuing for about 30 minutes.

Ibrahim al-Asiri is the Al-Qaeda bomb-maker thought to be working on the new 'stealth explosives' which have led to the heightened alert

'The problem was that lots of things were being taken from people's bags to additional checks - probably because of the tighter control, but it's better to be safe than sorry.'

And Kenny Stafford, 25, from Dumfries, added: 'My laptop was given an extra check by the security officials. It probably took me about 30 minutes to get through and I had to run to my gate.'

It is feared the scenes could become commonplace during a summer of travel chaos following a security alert over bombs that 'cannot be detected' by traditional scanners.
The Department of Transport introduced tougher checks after US security officials said they fear bombmakers from the Yemen-based 'Al Qaeda in the Arabian Peninsula' (AQAP) group have figured out how to turn phones and other devices into 'undetectable' explosive devices.
American officials are also concerned that hard-to-detect bombs could be built into shoes and have previously raised fears that explosives may be surgically-implanted into extremists' bodies.
Authorities are now hunting a Saudi bomb expert thought to be a leading figure in Al Qaeda's bomb-making team.
Ibrahim Al-Asiri, 32, who has survived numerous assassination attempts, is understood to have perfected a device which can be sewn into a human body making it almost impossible to detect by airport security scanners.
The technology is already thought to have reached British jihadists in Syria and Iraq. It is now feared they will return to target flights from the UK.

US officials say iPhones (left) and Samsung Galaxy phones (right) could be subject to greater checks

In 2010, an Al Qaeda group crammed explosives into computer printers before smuggling them onto planes

The alert led to the number of sophisticated body scanners at British airports being raised from ten to 21 yesterday.

Manchester Airport has insisted today's queues were unrelated to any security changes and were due to the busy summer holiday season.
A spokesman said: 'July is a busy month for the airport and many passengers will be using services from Manchester over the next few weeks.
'Our security officers are on hand to give advice and we ask that passengers work with us so that we can ensure we get people to their gate on time, in a safe manner.
'We ask that passengers leave enough time and arrive two hours before their flight to ensure that we keep the security process moving.'
Glasgow Airport said they had no reported issues and a spokesman for Gatwick said customers were only having to wait at baggage reclaim.
France today followed Britain in increasing security on flights to the US, with the French civil aviation authority announcing stepped-up security measures 'for the summer period'.

DM