A German government report reveals that airline pilots in 222 cases this year have prevented the deportation of failed asylum seekers and illegal immigrants because they refused to fly them home.

At the Berlin-Tegel airport alone, from January to September 30th, 23 deportations have been stopped by pilots unwilling to take migrants back to their countries of origin. The pilots, who work for airlines like Lufthansa, are allowed to refuse to fly passengers if they feel they are under duress, broadcaster RBB reports.

In Frankfurt, one of the main hubs for deportations and the busiest airport in Germany saw 143 cases of pilots refusing to fly with the migrants onboard and Dusseldorf had 40 cases. The information comes after a request by members of the far-left Die Linke party to the federal government earlier this week.

“We have to prevent anyone from being freaked out during the flight, and we have to protect the other passengers as well,” a pilot, who wished to remain anonymous, said.

According to Lufthansa group spokesman Helmut Tolksdorf, pilots are allowed to refuse service to troublesome or intoxicated passengers but are supposed to take on deportees.

So far this year, only 799 failed asylum seekers and illegal migrants have been deported by aeroplane from Berlin and 4,821 from Frankfurt.

Some have estimated that the total number of failed asylum seekers in Germany could be as high as 250,000 but some, like conservative Bavarian Christian Social Union leader Horst Seehofer, has called mass deportations “almost impossible”.

How are you getting on with those deportations, Germany? https://t.co/k4gmO5kh2q — Breitbart London (@BreitbartLondon) October 27, 2017

German Chancellor Angela Merkel promises to increase deportations last year but has struggled to come anywhere near her target of 100,000. In Hamburg, where the government has spent millions of euros on a new deportation centre, only 84 migrants were deported according to reports from earlier in the year.

In Saxony, despite having a list of 14,000 individuals set to be deported to Afghanistan, a 180-seat aircraft was used to deport only 14 people costing taxpayers thousands of euros.