He did not attend a meeting yesterday of his ruling Liberal Democratic Party (LDP), which picked Mr Yasuo Fukuda, 71, a moderate veteran lawmaker, as his successor.

In a letter read out at the meeting, Mr Abe pledged to work to support Mr Fukuda, who is expected to be formally chosen by Parliament tomorrow as Japan's new prime minister.

'I apologise to party members and especially to all the Japanese people that I created this political vacuum after I announced my resignation at such an important time,' said Mr Abe, who voted by absentee ballot, in the letter.

'I beg you to excuse me for being absent from today's general meeting due to my lingering hospitalisation and medical treatment.

'I hope the party will strongly press forward policies for the betterment of people under the new leadership,' he said. 'I will continue making my contribution as one Member of Parliament.'

Mr Abe, who spent his 53rd birthday in hospital on Friday, is Japan's youngest prime minister in recent times. He checked into the hospital a day after his resignation on Sept 12. Doctors said he had gastrointestinal problems caused by extreme fatigue and stress.

AGENCE FRANCE-PRESSE