TOKYO - JAPAN'S gaffe-prone Prime Minister Taro Aso was forced to apologise on Thursday after criticising the elderly for not staying fit, risking a backlash in the rapidly greying country.

The 68-year-old outspoken conservative has come under fire in recent weeks for appearing to insult doctors, parents, and even members of his own ruling party.

In the latest gaffe, Mr Aso took a swipe at the country's fast ageing population, which places a huge burden on the country's debt-laden finances.

'Why do I need to pay the (medical costs) for (sick elderly patients) who don't do anything, who just sit there eating and drinking?' Mr Aso asked an economic advisory panel in remarks that were released on Wednesday.

'There are 67-, 68-year-olds who dodder to class reunions and consult doctors a lot,' he said. 'I walk every day and do other things. But I'm paying more taxes.' Mr Aso, the scion of a wealthy family, on Thursday retracted his comments.

'I apologise for having offended the feelings of those who are currently sick,' he said.

'The point I was making was that there is a very large gap between people who maintain good health and who pay attention to prevention, and those who don't. The media picked up only a part of my remarks,' he added.

His remarks drew the ire of the opposition, which is pressuring the premier to hold snap elections.

Mr Aso, whose public approval ratings are sliding, 'seems to not understand the ethos of fraternity, of co-existence. It is a mystery why this kind of person is appropriate to be the prime minister,' said Democratic Party secretary general Yukio Hatoyama.

Mr Aso's right hand man, Chief Cabinet Secretary Takeo Kawamura, indicated that the prime minister's gaffes were likely to continue.

'The prime minister has that kind of personality, so I'm sure there will be similar remarks from now on. I need to make more efforts to have (you) understand what his true intentions are,' he told reporters.

Last week Mr Aso said doctors, a key support group for the ruling party, were 'lacking common sense.' Last year he was criticised for joking about patients suffering from Alzheimer's disease. -- AFP