Air Berlin's creditors have picked German flagship carrier Lufthansa and Britain's EasyJet as possible buyers for the insolvent carrier's aviation business and will negotiate with them for the next three weeks. 

"Authority was granted to conclude one or more agreements with one or more of these bidders," Air Berlin said in a statement last night. 

Talks over its other Air Berlin assets, such as its aircraft maintenance unit, will continue with other bidders, it said. 

Air Berlin, which has about 8,000 employees and operates 144 mostly leased planes, filed for insolvency in August after major shareholder Etihad pulled the plug on funding. 

Two sources familiar with the matter had told Reuters on Thursday that Lufthansa was set to pick up a large part of the carrier. 

Lufthansa's CEO said earlier that the carrier wanted to secure the 38 crewed planes it leases from Air Berlin, and was interested in a further 20-40 short-haul planes. 

Air Berlin said negotiations with Lufthansa and EasyJet would continue until October 12, which means Air Berlin's board may not make a final decision on September 25 as had been expected. 

The news comes ahead of a national election on Sunday in which Chancellor Angela Merkel is set to win a fourth term.

The prospect of getting access to Air Berlin's airport slots, planes and crews had drawn interest from those airlines and other investors.

These include former Formula One driver Niki Lauda, jointly with Thomas Cook's German airline Condor, and aviation entrepreneur Hans Rudolf Woehrl.

Also, two people familiar with the matter had told Reuters earlier this week that Aer Lingus and British Airways owner IAG had joined the field of bidders for parts or all of Air Berlin. 

Bidders had been especially interested in Air Berlin subsidiary Niki, which operates short-haul flights from Germany and Austria to tourist hot spots. 

The deadline for bids for its maintenance unit, which has about 850 employees, has been extended to October 6, Air Berlin said.