Talks over Air Berlin's remaining assets will continue over the weekend, with the goal of presenting a proposal to the insolvent German carrier's creditors on Tuesday, its chief executive Thomas Winkelmann said. 

Air Berlin filed for insolvency in August and is being carved up among several buyers. Lufthansa has already agreed to buy large parts of the airline. 

The group had set a deadline of today for exclusive talks to sell up to 25 A320 aircraft to Britain's EasyJet as well as to find a buyer for Air Berlin's cargo marketing businesses and aircraft maintenance businesses. 

Several people familiar with the matter told Reuters that family-owned firm Zeitfracht and maintenance group Nayak were together poised to strike a deal to buy the cargo marketing platform and maintenance units. 

Lufthansa said today that it may remain a major customer to the maintenance business after it has been sold, which is positive news for any possible buyer. 

"If there is a buyer, we will of course try to continue booking capacity at Air Berlin Technik or its successor organisation as much as possible," Lufthansa board member Thorsten Dirks said. 

Dirks, who is also chief executive of Lufthansa's budget unit Eurowings, said the group had discussed the matter with parties interested in the maintenance business as well as with Air Berlin's administrator. 

The maintenance unit has around 850 full-time equivalent positions, or around 1,200 staff.