Security is being stepped up at UK airports following pressure from the US.
The Department of Transport has issued a statement saying security will be tightened but would not provide further detail.
"We have taken the decision to step up some of our aviation security measures," it said.
"For obvious reasons we will not be commenting in detail on those changes."
It said the "majority of passengers" should not experience significant disruption.
The security threat level remains at ‘substantial’, which means an attack is a strong possibility.
"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," added the Department of Transport.
The changes come after the White House voiced fears that terrorists are planning to bring down a plane with the help of European jihadists returning from Syria.
President Barack Obama told American TV news channel ABC he believes there is a real threat to the US of Europeans becoming radicalised in Syria and using their EU citizenship to travel more freely than Arab or Pakistani jihadists.
"They’ve got European passports. They don’t need a visa to get into the United States," he said.
The Department of Homeland Security said changes to aviation security in the US would be made in the "upcoming days".
"We will work to ensure these necessary steps pose as few disruptions to travellers as possible," it said.
"We are sharing recent and relevant information with our foreign allies and are consulting the aviation industry."
Tighter security could mean passengers travelling to the US are forced to arrive earlier at UK airports or at the gate to allow time for extra security checks, which might lead to longer queues.
The US government is also considering installing more armed US air marshals on flights between the UK and the US.
Airlines said they are ready to bring in any new measures when instructed.
A Virgin spokeswoman said: "Whilst Virgin Atlantic does not disclose specific security details, our arrangements are under constant review and can be adapted at short notice should there be a need to do so."
