Air France-KLM's operating loss widened to €303 million in the first quarter of 2019, from €118 million experienced in the first three months last year.
The group also posted a 1.9% drop in unit revenue for the quarter, which the company has blamed the drop on higher fuel costs and price competition.
Air France-KLM said its fuel bill grew by €140 million to €1.2 billion in the quarter.
The group did however post a revenue rise of 3.1% to almost €6 billion.
Air France-KLM chief executive Ben Smith said: “The first quarter has been challenging for the European airline industry including the Air France-KLM Group... Substantial industry capacity growth in the off-peak business period led to unit revenue pressure.”