Japan Airlines Corp., Asia's biggest carrier by sales, is asking workers to take unpaid leave at its international unit for the first time in four years amid slumping demand for air travel.

Japan Airlines International Co., with about 16,200 employees, offered to let cabin attendants, cockpit crew and ground staff in Japan apply for one or two months of unpaid leave starting next month, spokesman Stephen Pearlman said in an interview Thursday. He declined to say how many employees are expected to take the leave.

The move comes after the carrier flew 17.6 percent fewer international passengers in November, the biggest tumble since the SARS and bird flu outbreaks of 2003 slashed travel.