Japanese Prime Minister Shinzo Abe was admitted into a Tokyo hospital on Thursday noon for functional gastrointestinal disorder.

Doctors said Abe was "extremely weak" and needs to be hospitalized for three to four days, a hospital official told reporters at a press conference.

The prime minister went to see doctors at Keio University Hospital for feeling sick and received physical checkup in the morning, one day after expressing his intention to resign.

Abe went to hospital on advice of his private doctors, who concluded in recent days that the prime minister's fatigue has reached a peak and should undergo a thorough examination, Kyodo News reported, quoting Chief Cabinet Secretary Kaoru Yosano.

Shortly after Abe's announcement of resignation, Yosano said the prime minister made the decision out of health reason. However, Abe himself did not mention any physical problems at Wednesday's press conference.

Japanese media quoted sources as saying that the premier felt unwell with his stomach recently and has even received intravenous fluids in the past week.

(Xinhua News Agency September 13, 2007)