Japanese Prime Minister Shinzo Abe is to resign because of ill health, public broadcaster NHK and other Japanese media reported Friday.

Speculation about the conservative leader’s condition has swirled of late after recent visits to the hospital. He is known to have battled chronic ulcerative colitis.

NHK reported that medical tests conducted on Aug. 17 revealed Abe’s colitis had deteriorated. An alternative medicine was prescribed when Abe returned to the doctor a week later but the prime minister was told treatment would take a year, the broadcaster reported.

Abe is expected to provide more details at a news conference later Friday.