An Austrian court, at the urging of a passenger rights group, had decided earlier that the insolvency had to be handled mainly in Austria, a move that could unravel the agreed sale to British Airways owner IAG (>> International Consolidated Airlines Group).

"The opening of this case contradicts European insolvency regulation," Lucas Floether said in a statement.

"In the foreground, however, is the fact that the sales contract that has already been concluded achieves legal status for the Niki operations and saves as many jobs as possible. Questions of competence are wholly secondary."

(Reporting by Georgina Prodhan; Editing by Ludwig Burger)