Photographers travelling back from the world?s biggest photography show, Photokina, were forced to cancel their return journey from Cologne in Germany after air traffic control problems hit UK airspace.

Visitors to the biennial photographic kit fest, who were due to return yesterday, were told to make alternative travel plans because their plane had been cancelled.

And, this morning, any hopes for a return to normality at Cologne/Bonn airport were dramatically dashed when it was reported to be at the centre of a terror alert.

German commandos are understood to have stormed a KLM plane and arrested two terror suspects.

The news will come as a triple blow to Photokina visitors who had already faced road closures on their arrival in the city when tens of thousands protested in Cologne last weekend.

Three thousand extra police were drafted in after German citizens protested against

an anti-Islam congress in the city.