Japan will limit asylum seekers' right to work from Monday, making changes to its refugee system that are likely to swell the numbers of those in detention centres, the justice ministry said, prompting refugee groups to flag humanitarian concerns.

The move to tighten one of the developed world's toughest refugee systems, which accepted just ten during the period from January to September last year, is a bid to clamp down on what Japan views as a system of back-door immigration.From Monday, the right to work is to be limited only to those Japan regards as bonafide refugees, while repeat applicants and those failing initial checks will be held in detention centres after their permission to stay in Japan expires, the justice ministry said.

Asylum seekers with valid visas now receive renewable permits to work in Japan while their refugee claims are reviewed - a system the government says has spurred people to seek asylum as a means of finding jobs.

The number of asylum seekers in Japan has risen steadily in recent years to a record, with more than 14,000 applicants between January and September last year, an increase of almost 80 percent from the year earlier period, ministry data shows.