Gaffe-prone Finance Minister Taro Aso was again caught taking a swipe at the elderly, saying last week that he wondered how much longer a 90-year-old person intends to live.

The outspoken Aso, who is also deputy prime minister, made the comment at a Liberal Democratic Party rally in Otaru, Hokkaido, on Friday, where he said: "I recently saw someone as old as 90 on television, saying how the person was worried about the future. I wondered, 'How much longer do you intend to keep living?' "

His comments, part of a speech urging wealthy elderly citizens to spend more to spur the economy, drew immediate fire from Democratic Party President Katsuya Okada.

"This is an insult to the nation's elderly," Okada told reporters in Yufu, Oita Prefecture, on Saturday. "It's extremely disheartening that someone who cannot understand the public's concerns about nursing care is serving as finance minister."

During the Otaru rally, Aso pointed to the more than ¥1.7 quadrillion of personal assets held nationwide, saying the money needs to be spent.

"The biggest problem at the present is how everyone is staying put," he said. "If you don't spend the money you have, that money will mean nothing. What's the point of accumulating more wealth? Just looking at the money you have?"

Aso is no stranger to offending key electoral groups, young and old, and is known for having a thick skin. In 2013, at a government meeting on social security reform, he said the elderly "should hurry up and die" as they are costing taxpayers huge sums for medical care.