The alert from the state department will remain in place until February 24 2016.

It said “current information” suggested that Islamic State, al-Qaeda and Boko Harem amongst others continue “to plan terrorist attacks in multiple regions”.

A representative from the US state department told the BBC that there was “currently… no reason to believe that US citizens would be specifically targeted.”

A US worldwide alert is unusual, although it has happened before. The last was Christmas 2014 following an attack in Sydney, when US citizens were warned about the risk of “lone wolf” attacks.

It advises US citizens to "exercise vigilance when in public places or using transportation".  

They are also advised to "be aware of immediate surroundings and avoid large crowds or crowded places".

"Authorities believe the likelihood of terror attacks will continue as members of ISIL/Da’esh [IS] return from Syria and Iraq," the state department said.

It comes after the recent massacres in Paris and Mali’s capital Bamako, as well as the downing of the Russian passenger jet over the Sinai peninsula in October.

Belgium has said that its capital Brussels will remain at the highest level of alert for another week, amid fears that militants could launch another attack like those that killed 130 people in Paris on November 13.