Airline passengers flying to the US have been told they should not suffer “significant disruption” because of a new security alert.
Airports with direct flights to the US, including UK hubs such as Heathrow, are tightening security measures due to a “credible threat” of a potential terrorist attack.
UK transport secretary Patrick McLoughlin said: “We have taken the decision to step up some of our aviation security measures. For obvious reasons we will not be commenting in detail on those changes.
“The majority of passengers should not experience significant disruption. There will be no change to the threat level, which remains at substantial.
“The safety and security of the public is our paramount concern. The UK has some of the most robust aviation security measures and we will continue to take all the steps necessary to ensure that public safety is maintained.”
The security warning came after the US Department of Homeland Security (DHS) said it was responding to a “credible” terrorist threat but would give no further details.
There have been reports in the US that groups linked to al-Qaeda had been developing bombs which could be smuggled on to aircraft.
“Aviation remains an attractive target to global terrorists, who are consistently looking for ways to circumvent our aviation security measures,” said a spokesman for the DHS. “As always, DHS continues to adjust security measures to fit an ever evolving threat environment.”
DHS secretary Jeh Johnson said in a statement: “I have directed TSA (Transportation Security Administration) to implement enhanced security measures in the coming days at certain overseas airports with direct flights to the United States.
“We will work to ensure these necessary steps pose as few disruptions to travellers as possible. We are sharing recent and relevant information with our foreign allies and are consulting the aviation industry.”
Heathrow said in a statement: “The airport continues to operate as normal.” The airport also refers passengers to its current security procedures including the restrictions on taking liquids onboard, which were first introduced in 2006 in the wake of a plot to bomb up transatlantic aircraft using drinks bottles filled with explosives.
Gatwick said: "We’re continuing to operate as normal."