Japan's prime minister, Taro Aso, has criticized ailing elderly people for not staying healthy, a comment that could further damage his flagging support in the world's most rapidly ageing country.

Japan's gaffe-prone prime minister, Taro Aso, has criticized ailing elderly people for not staying healthy, a comment that could further damage his flagging support in the world's most rapidly ageing country.

In the space of a couple of weeks, 68-year-old Aso has offended doctors and parents of small children and upset various factions in his own party, in a string of verbal blunders that have left some analysts wondering about his grip on power.

Commenting on Japan's ballooning medical expenses, the Aso told the government's top economic advisory panel that he tried to stay healthy by taking a daily walk, and questioned why his tax payments should go to fund medical care for others who were more lax.

"Going to class reunions at the age of 67 or 68, I see feeble old people who go to the doctor's a lot," Aso told the panel, minutes of the November 20 meeting showed.

"My medical expenses are a lot lower because I walk and so on," said Aso, who comes from a wealthy family. "Why should I have to pay for those who just eat and drink and make no effort?"

Aso, 68, added that incentives should be introduced for those who maintain a healthy lifestyle.

Aso's top aide, Chief Cabinet Secretary Takeo Kawamura, told a news conference on Thursday that the prime minister had wanted to stress a need for self-help efforts to maintain health and had not intended to criticize sick people or Japan's medical system.

Kawamura, however, added: "If his comments hurt any feelings, I apologize. But I would like to say that was not his intention."

Asked how he feels about being asked repeatedly to explain Aso's comments in recent weeks, Kawamura gave a bitter smile and said: "It would be better if I did not have to explain them.

"But it's part of his character and there may be various comments from now on, and it is my job to make efforts to let everyone understand his real intention."

Just over a week ago, Aso was forced to apologise after accusing doctors, an important political interest group, of lacking common sense. Last year he was criticized for joking about Alzheimer's disease.

Aso had been expected to call asnap election after taking office in September following the sudden resignation of his predecessor, Yasuo Fukuda.

But the fallout from the world financial crisis and his party's weak performance in opinion polls have delayed the poll.