Security at airports with direct flights to the United States has been tightened in response to a “credible threat” to aviation.

The move includes some airports in the United Kingdom, with transport secretary Patrick McLoughlin confirming measures had been put in place to protect the public.

A statement explained: “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 news follows media reports in the US that al-Qaeda affiliates in Syria and Yemen are developing bombs to smuggle on planes.

Jeh Johnson, secretary of US department of homeland security said the changes were a response to a “real time” and “credible” threat but it could not comment on specific intelligence matters.

It is understood airport terminals will look normal and problems like those encountered when the limit on liquids carried on board was introduced are not expected.

Johnson added: “We are sharing recent and relevant information with our foreign allies and are consulting the aviation industry.

“These communications are an important part of our commitment to providing our security partners with situational awareness about the current environment and protecting the travelling public.

“Aviation security includes a number of measures, both seen and unseen, informed by an evolving environment.

“As always, we will continue to adjust security measures to promote aviation security without unnecessary disruptions to the travelling public.”