A receiver of insolvent German airline Air Berlin said he is optimistic about the sales process of the airline's subsidiary Niki after a number of would-be investors stepped forward under a fast-approaching deadline. 

"I conclude from the great demand in the investors' process that there is a good chance of a last-minute rescue for Niki, despite the heavy time pressure," Lucas Floether said.

He made his comments in an interview today's edition of German daily Sueddeutsche Zeitung. 

Niki applied to open insolvency proceedings last week after Lufthansa dropped a bid for the Austrian holiday airline. 

Floether said Niki's insolvency had created a new situation. 

"The airline is becoming more interesting because disadvantages such as existing contracts can now be terminated," he said. 

"Also, the double-digit million euros sum, which Lufthansa invested in Niki, does not have to be repaid because it has become an insolvency claim." 

The parties are under pressure to agree a deal before Niki loses its take-off and landing rights, its most attractive assets, which is believed to be at risk of happening within days.

While deadlines were ambitious, Austria's air navigation supervisor, the Austro Control authority, was at liberty to lengthen a seven-day deadline for the operating licence to be withdrawn until after the upcoming holidays, Floether said. 

Motor racing driver Niki Lauda, who founded Niki in 2003, joined the group of interested parties by telling German business daily Handelsblatt in its Monday edition that he aims to bid for the airline next Wednesday. 

He said he had talked to another Air Berlin administrator, Frank Kebekus, on Friday, telling him he was ready to act quickly. 

On Saturday, German logistics firm Zeitfracht and maintenance group Nayak confirmed they were interested in some Niki assets, including Niki Technik, and crews. 

Lauda also told Handelsblatt he would engage in the talks initially without British holiday group Thomas Cook, also among the interested parties, to speed things up. 

"But logically, I am in contact with Thomas Cook and its (German) subsidiary Condor," he added. 

Ryanair has also expressed an interest. 

Lufthansa scrapped plans to buy Niki due to European Commission competition concerns, even after providing the carrier with tens of millions of euros in financing to keep its planes in the air until the deal was completed. 

The administrators for Air Berlin have since been working to find a new buyer for Niki's assets - which include valuable take-off and landing slots at airports such as Duesseldorf, Munich and Vienna - trying to clinch a deal before Niki loses its slots.