About 4,000 pilots at German airline Lufthansa have gone on strike for four days in a dispute over job security.

德国汉莎航空公司大约4000名飞行员因工作保障纠纷将开始为期四天的罢工。

Lufthansa operates about 1,800 flights a day

The carrier has cancelled about 3,000 flights and has warned of delays both domestically（国内地，家庭式地） and internationally.

Lufthansa's offer of negotiations¹ with the pilots was not taken up on Sunday before the strike began at midnight (2300GMT).

The pilots work at Lufthansa, Lufthansa Cargo² and its low-budget subsidiary（子公司，附属机构） , Germanwings.

The airline normally offers about 1,800 flights daily - of which 160 are long-haul（长途的，长时间的） trips.

Before the strike began German Transport Minister Peter Ramsauer warned that it would hurt the country's economy as well as Lufthansa's reputation.

The airline - the biggest in Europe - fears the strike could cost it about 25m euros (£21.9m; $34m) per day.

The Cockpit Union says the airline is increasingly relying on foreign pilots who fly for less pay.

The pilots are not due to return to work until midnight on Thursday.

Last-minute failure

Lufthansa was offering train journeys to domestic air travellers, and attempting to rebook international passengers on other airlines.

Frankfurt and Munich airports will be the worst hit.

Hours before the strike began, Lufthansa tried a last-ditch（坚持到最后的，最后防线的） effort to resume talks.

"We are open to talks without preconditions（先决条件） ," Lufthansa spokesman Klaus Walther said.

He added that "if Cockpit（驾驶舱） withdrew its list of unworkable and illegal demands... an agreement could be found quickly".

The union wants all Lufthansa pilots, including those working for affiliated³（有关联的，附属的） airlines overseas, to be paid the same.

Its suggestion on Sunday that that particular issue be put aside while other issues were discussed was rejected by managers, according to AFP news agency.

Cockpit spokesman Joerg Handwerg said: "The Lufthansa management is not interested in dialogue but will not say so openly."