Former Prime Minister Ryutaro Hashimoto was hospitalized early Saturday morning with a high fever caused by a cold, his aides said.
Hashimoto, 65, has suffered from a slight cold in recent days, they said. He will need to rest at a Tokyo hospital for between seven and 10 days but is in stable condition, they said.
He underwent heart surgery at the hospital in February last year, but his present condition is not related to his heart problems, they said.
He first won a House of Representatives seat in 1963, and served as prime minister between January 1996 and July 1998.