German tour operator TUI warned Tuesday that it does not expect Boeing to deliver any 737 MAX aircraft before September, as the plane builder scrambles to regain regulatory approval after two deadly crashes.

"We no longer expect any Boeing MAX deliveries" before TUI's financial year ends in September, chief executive Fritz Joussen said ahead of the group's annual shareholder meeting.

With the package holiday group forced to rent replacement aircraft for longer than expected, costs stemming from the 737 MAX's grounding are expected to mount to between 220 and 245 million euros ($240-267 million) over the year.

Steve Dickson, head of the US Federal Aviation Administration safety regulator, said last week that a certification flight for the 737 MAX could take place in "a few weeks".

The model has been grounded worldwide since March last year after two crashes that claimed 346 lives.

Still grounded...
Still grounded... GETTY IMAGES NORTH AMERICA / David Ryder

TUI reported an operating loss of 147 million euros in October-December, traditionally the off season for package holiday firms.

The loss was almost 80 percent worse than the same period last year, weighed down especially by 45 million euros of costs related to the 737 MAX grounding.

But TUI added that it was in talks to recover some of the cash from Boeing.

Looking ahead to the full year, TUI expects an operating profit adjusted for special items of between 850 and 1.05 billion euros.

The group has seen 14 percent growth in bookings since competitor Thomas Cook went bust.

"The travel market in Germany and the United Kingdom should shrink, but we'll be able to gain market share," CEO Joussen said.