Japan Airlines Co. said the release of new operating slots at Tokyo's Haneda airport has created a capacity glut likely to persist for another 18 months, weighing on average fares and earnings.

"There was a large increase in the supply, and demand has not kept up at this point in time," JAL Chairman Masaru Onishi said Monday during an interview in Qatar. "The same happened for international flights. Hence we believe that for this fiscal year, business will be a little difficult for us."

Excess flights at Haneda, which handles the bulk of Japan's domestic and short-haul services, come as JAL seeks to improve its financial position after emerging from bankruptcy protection in 2011. The airline is "financially healthy" but will focus on improving its cash position and credit rating before boosting shareholder returns, Onishi said.