Star Alliance carrier Lufthansa's operating losses more than doubled to €381 million ($501.6 million) in the first quarter of 2012.
The German airline's loss for the first three months of the year compares to an operating deficit of €169 million at the same stage last year.
Revenues were up 5.6% to €6.6 billion, but the growth in sales was outpaced by higher costs, especially due to higher fuel prices, the carrier says.
Lufthansa made a net loss of €397 million in the first quarter. This marked an improvement over last year when the company lost €507 million.
This year's deficit includes €2 million from the former subsidiary British Midland, which Lufthansa sold to International Airlines Group last month.
Lufthansa expects to increase its revenues for the total year and achieve an operating profit in the "in the mid-three digit million euro range". However, this outlook does not include potential additional costs due to the Score restructuring programme, the airline warns.