Japan's PM in hospital as rumours rife over his swift decision to quit

Japan's outgoing Prime Minister, Shinzo Abe, has been taken to hospital with exhaustion as political confusion reigns within the ruling bloc and rumours swirl about what lay behind his abrupt decision to quit.

Mr Abe, who stunned Japan on Wednesday with his resignation announcement and left his party, the ruling Liberal Democrats (LDP) scrambling for a successor, is being treated in a Tokyo hospital for a stress-induced intestinal disorder, according to his doctors.

"He is suffering from symptoms including abdominal pain, digestion problems and lack of appetite," said Doctor Toshifumi Hibi. "These symptoms can be attributed to physical exhaustion and psychological stress."

The diagnosis shed some light on the 53-year-old Prime Minister's shock decision, despite a promise two days earlier to stay in power. It also helps explain his sometimes odd behaviour during Diet (parliament) debates this week, when he refused to stand for questions and frequently left the room.

But political commentators continued to speculate throughout the day on other possible motives for the mysterious resignation, with some suggesting that the prime minister may be fleeing yet another money scandal.

Four of Mr Abe's cabinet ministers resigned amid allegations of financial misdeeds in just 12 months of government and he is also being investigated by at least one magazine for allegations that he had failed to pay tax on income inherited from his father.

The rumours have added to the LDP's problems as it begins the search for a new party head, who will almost certainly become the next Prime Minister.

Last night, the party announced it would hold its leadership election on 23 September.

Secretary General Taro Aso, a hawkish nationalist and former foreign minister, is seen as the front runner but there were growing signs yesterday his support was slipping. Former LDP Secretary General Makoto Koga was one of several influential party elders who said Mr Aso had been tainted by his close association to the Abe government and would have to share the blame for its failures.

The Finance Minister, Fukushiro Nukaga, and the liberal LDP veteran Yasuo Fukuda are also tipped to run for the leadership.