Fourteen inmates in an Osaka immigration detention center are on hunger strike over what they call "inhumane conditions" including poor medical care, drawing fresh attention to the country's detention system.

The detainees launched their hunger strike at the center on Monday over the rejection of their applications for provisional release, the Osaka Regional Immigration Bureau said.

The hunger strikers are also protesting against inadequate medical care and long-term detention, a detainee at the center and Nobukazu Nagai, of the Provisional Release Association in Japan, told Reuters.