(Reuters) – Lufthansa pilots on Wednesday announced a third consecutive day of strikes this week, forcing hundreds of flight cancellations and ramping up pressure on management in a long-running row over early retirement benefits.

The German airline is trying to cut costs and expand budget operations as it competes with low-cost carriers like Ryanair and easyJet in Europe and Gulf rivals such as Emirates.

But its attempts to renegotiate collective labor agreements, including retirement benefits, have been resisted by pilots at union Vereinigung Cockpit (VC) who staged 10 strikes last year.

The union already staged a strike on short and medium-haul flights on Wednesday and plans a long-haul strike on Thursday. It said late on Wednesday it was calling for a walkout on Lufthansa short and medium-haul flights all day on Friday.

Wednesday’s strike, the second this year, also targeted short and medium-haul operations at Lufthansa’s namesake brand, with the carrier cancelling 750 of a scheduled 1,400 flights. Lufthansa canceled 84 of its 153 long-haul flights planned for Thursday, but said it would operate all cargo flights.

VC stressed it did not seek to block the company’s strategic decisions, only set contract terms for pilots.

“Competition must not lead to a sell-out of the values that have helped make Lufthansa one of the world’s leading airlines,” VC spokesman Joerg Handwerg said in a statement.

Lufthansa in response asked pilots to return to the negotiating table.

Lufthansa units Germanwings and Eurowings would not be affected by the Friday strike, the union said.

Equinet analyst Jochen Rothenbacher estimates the latest strikes are costing the carrier around 15 million euros a day in lost profit and said the dispute could last a long time.