Berlin-based airline Germania has filed for bankruptcy and cancelled all flights with immediate effect, the company said early on Tuesday.

The airline with 37 aircraft had flown mainly Mediterranean, North African and Middle Eastern holiday routes for German sun-seekers on package trips, and said it transported more than four million passengers a year.

"Unfortunately, we ultimately failed to successfully complete our financing efforts to meet short-term liquidity needs," said managing director Karsten Balke in a statement.

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

The company blamed "unforeseen developments" for its cash shortage such as "steep kerosene price increases over the summer of last year with a simultaneous fall of the euro against the US dollar" as well as a high number of technical services required by its fleet of aircraft.

Ms Balke said "we especially regret the impact that this step has on our employees", who had done their best to ensure reliable and stable flight operations.

"I thank you all personally and with all my heart. I apologise to passengers who can not take their Germania flight as planned," said Ms Balke.

The ailing company, which had reported financial woes in January, said it had filed for bankruptcy with a Berlin court late on Monday and that all flights were halted overnight.

Affected passengers who booked as part of a package holiday were told to contact their tour operator for replacement flights.

"Regrettably, for passengers who purchased their ticket directly from Germania, there is no entitlement to replacement transport due to the current legal situation," the airline said.

The company's subsidiaries, Swiss Germania Flug and Bulgarian Eagle, are unaffected, the statement said.

The small carrier's bankruptcy comes after Air Berlin, formerly Germany's second-largest airline, went bust in 2017 after shareholder Etihad Airways withdrew funding following years of losses.