"We are ready to go for further strikes, including with pilots, if necessary," she said at a press briefing in New York.

Trade union Verdi went on strike last week to push through demands for a 5.2 percent pay rise for 33,000 cabin crew and ground staff at Lufthansa Cargo, Lufthansa Technik, Lufthansa Systems, catering unit LSG Sky Chefs and ground crews.

Lufthansa, now implementing a restructuring, has also been in talks with pilot union Cockpit for nearly a year over a new wage agreement and recent union comments have signalled some impatience.

"We will not agree to short-term harmony if there is long-term further burdening," Menne said.

Asked about the cost of last week's strike, Menne said she did not yet have a figure, but that a strike by cabin attendants during peak season last year had cost it 33 million euros.

Lufthansa is cutting 3,500 jobs, revamping low-cost carrier Germanwings and bundling procurement for its airlines. The restructuring programme, dubbed SCORE, is intended to help to boost operating profit to 2.3 billion euros (1.97 billion pounds) in 2015 from 524 million euros last year.

Menne also said that the company would definitely not be selling 100 percent of catering unit LSG Sky Chefs and is looking to expand into hospital, school and train food, possibly with a partner.

An investment banker told Reuters in June last year that LSG Sky Chefs, the world's biggest airline catering company with 2.3 billion euros in annual revenue, could be put on the block.

Luthansa has said the business is not core but makes a valuable contribution to the group.

(Reporting By Alwyn Scott, Writing by Marilyn Gerlach; Editing by Christiaan Hetzner and David Goodman)