TOKYO (Reuters) - Dozens of detainees at a Japanese immigration center were on hunger strike on Thursday in protest against prolonged and multiple detentions, drawing fresh attention to the policy toward immigration.

FILE PHOTO: Detainees are seen through a hatch at the Tokyo detention center which is part of Tokyo Regional Immigration Bureau in Tokyo, Japan, December 2, 2015. REUTERS/Yuya Shino/File Photo

Some of the hunger strikers were asylum seekers and others had lived in Japan for decades as migrant workers, said Mitsuru Miyasako, head of the Provisional Release Association in Japan.

More than 20 detainees launched their hunger strike at the Tokyo Regional Immigration Bureau on Tuesday, with more than a dozen joining them on Thursday, one of the protesters and an activist told Reuters.

Protests and hunger strikes are rare in Japan, which prizes social stability. Immigration, seen by some Japanese as a threat to security, is a controversial subject in a country where many pride themselves on cultural and ethnic homogeneity.

Justice Ministry official Shigeki Otsuki confirmed some detainees were refusing to eat.

Otsuki said he could not immediately say if detentions were rising, but said 387 men and 189 women were currently held at the Tokyo center.

“We need change. We need to stop this system,” one of the hunger strikers told Reuters. The inmate was detained once for 10 months.

The strike follows two hunger strikes protesting poor medical care in detention at a center in Osaka. It also comes after a recent death of a Vietnamese detainee at a different detention facility provoked criticism about conditions inside.

A Reuters investigation last year into the death of a Sri Lankan at the same Tokyo center revealed serious deficiencies in medical treatment and monitoring in the immigration detention system.

Japan accepted just 28 asylum seekers last year from a record 10,901 applications, throwing a spotlight on the nation’s reluctance to accept foreigners.