Longer lifespans, falling fertility rates and growing ranks of elderly people in Asia can pose problems as serious as the impact of climate change, a leading expert warned Monday.

Yves Guerard, secretary general of the International Actuarial Association, said at a pensions industry conference in Singapore that the ageing issue was a "big, immediate, urgent problem" for the world's most populous region.

"I will compare that with climate change. We prefer not to believe in that because it's inconvenient," he said, referring to former US vice president Al Gore's celebrated environmental documentary "An Inconvenient Truth".

Problems linked to ageing populations will complicate Asian economies' recovery from the global financial crisis, said Guerard, whose organisation's members deal with complex insurance forecasting systems.

"Longevity increases combined with the decrease in fertility are pushing up the dependency ratio and the burden of the recovery," he said.

Countries with a large number of elderly people and a low birth rate will face demographic and economic problems supporting a large number of seniors, Guerard said.

Tan Hak Leh, deputy president of the Life Insurance Association of Singapore, said Asia's elderly population would far outstrip those in the rest of the world in 40 years.

"Asia's population of those above 60 years old is estimated to quadruple by 2050 to 1.2 billion people... four times the size of senior citizens in the US and Europe combined," he warned at the conference.

Japan, Singapore, South Korea and Hong Kong are among the world's 10 fastest-greying territories, Tan said.

Guerard said efforts to solve the "longevity problem" by raising the retirement age to allow the elderly to continue contributing economically were making slow progress.

"Countries have been very slow in moving up the retirement age, and even those that move it up move it in a very timid way," he said.

"When you increase the retirement age by two years, you are not catching up very much in increases in longevity."

Australia on Monday unveiled a 43 million Australian dollar (38 million US) plan to keep older people in the workforce in a bid to ward off an economic slowdown expected as the growing population ages.

Treasurer Wayne Swan said Australia's population was expected to rise by 14 million to 36 million by 2050 with a much higher proportion aged 65 or over, leaving fewer workers as health costs soar.

"If we are going to get to the point where there is going to be 2.7 working Australians for every person aged over 65, not five as there currently are, now in anyone's book, that's a big challenge," he told reporters in Canberra.