Pilots at Lufthansa announced Monday plans for a four-day strike next month, continuing a labour battle over job outsourcing that badly disrupted Europe's airways in February.

The Cockpit Association, which had resumed talks with the German company under pressure from a labour-court judge, said they had been fruitless and the strike would resume April 13-16.

The union objects to efforts at Europe's biggest airline by turnover to shift work to wholly owned subsidiaries with lower pay scales, such as Lufthansa Italia, based in Milan, Italy.

The union represents most of the 4,500 pilots employed at the Lufthansa parent company, Lufthansa Cargo and Germanwings.

The union accused Lufthansa of offering nothing better than a 21-month pay freeze and a degradation of working-hour rules. It also charged that Lufthansa had breached past promises to the Cockpit Association.

But Lufthansa's chief labour negotiator, Roland Busch, said the company had offered to guarantee every pilot's job till 2012, which was 'pretty good' at a time when the airline must avoid any cost increases. The recession has hit passenger and cargo sales badly.

The four-day February strike was called off halfway through, but the difficulty of starting up cancelled flights again at short notice meant that the disruption continued for the planned duration anyway.

During earlier strike, Lufthansa cancelled well over half its scheduled flights, drafting in ex-pilots from management to fly as many big jets as it could. A Frankfurt labour court directed fresh talks, saying some demands by the pilots had no legal basis.