ABU DHABI, United Arab Emirates — Gulf carrier Etihad Airways and German airline Lufthansa are deepening their budding relationship with a $100 million catering partnership.

The one-time rivals announced the catering deal at a joint press conference on Wednesday in Etihad's hub of Abu Dhabi, the capital of the United Arab Emirates. They also signed a memorandum of understanding aimed at cooperation on aircraft maintenance.

The partnerships are noteworthy because Etihad owns a 29 percent stake in another German carrier, Air Berlin. Lufthansa's Eurowings and Austrian Airlines units reached a deal in December to lease 38 planes from struggling Air Berlin, starting this month.

Etihad and Lufthansa reached a code-sharing agreement in December.