The Berlin-based airline, which flew to destinations across Europe, Africa and the Middle East, transported more than four million passengers a year.

It blamed rising fuel prices and currency fluctuations as two factors.

"We ultimately failed to successfully complete our financing efforts to meet short-term liquidity needs," said managing director Karsten Balke.

"We very much regret that, as a consequence, we had no choice but to file for bankruptcy."

The company said that passengers who had booked flights as part of a package should contact their tour operator to make different arrangements, but added that people who booked directly with them were not entitled to a replacement flight.

It is another blow to the German air industry after the country's second biggest carrier at the time, Air Berlin, filed for insolvency in August 2017.

And it follows more recent problems among other budget carriers.

On Monday, Ryanair posted its first quarterly loss since March 2014, when announcing a net loss of €19.6m (£17.2m) for the last three months of 2018.

And last week, Norwegian Air announced that it wants to raise 3bn Norwegian kroner (£268m) through a rights issue to improve its finances.

Other airlines like Wow and Flybe are looking for buyers.