Essen

Charlotte von Essen, the head of Sapo, said there was a "tangible risk that the security situation can deteriorate further" in a way that may be hard to predict.

Beyond airports, Verdi has also called for strikes in waste collection across several German cities, including Berlin, Essen and Kiel, where bins have gone unemptied since last week.

Earlier this year the BBC investigated the German connection to small boat crossings in the Channel with people smugglers operating in the west German city of Essen.

This is the “good price” offered by two small-boat smugglers to an undercover BBC journalist in Essen - a western German city where many migrants live or pass through.

"We had Margot, from Essen, who was living with us when I was born."