The number of Japanese centenarians has doubled in the past six years to a record high of more than 40,000, with women dominating the list of those whose lives have spanned more than a century, the government said Friday.

Japan will have 40,399 people aged 100 or older this month, surpassing the previous record of 36,276 last year, the Health and Welfare Ministry said in an annual report marking a Sept. 21 national holiday honouring the elderly. More than 86 per cent are women.

The number of centenarians in Japan has risen at an accelerating pace for nearly 50 years. The centenarian population surpassed 10,000 just 10 years ago, reached 30,000 in 2007 and grew another 10,000 in the past two years, the ministry said.

By 2050, Japan's centenarian population is expected to reach nearly 1 million, according to the U.N. projections.

"The data clearly show that Japan is aging rapidly and steadily, mainly because of progress in medical care and the high living standard since the end of World War II," ministry official Hiroyuki Ishii said.

Each new centenarian will receive a letter from the prime minister and a silver cup.

Though centenarians are healthier and more active than before, the rapidly greying population has fuelled concerns about Japan's overburdened public pension and medical care system.

Officials have stepped up programs that encourage older citizens to stay active and continue working. The government is gradually extending the retirement age to 65 from 60, and some advocate pushing it further to 70.

Japan has one of the world's longest life expectancies — 86 years for women and 79 years for men.

A 114-year-old woman from the southern island of Okinawa, whose name was not disclosed, holds the title of Japan's oldest citizen.

Japan's oldest man, 112-year-old Jiroemon Kimura from the ancient capital of Kyoto, is health conscious and still active. He rises early, reads newspapers every morning with a magnifying glass, enjoys talking to guests and closely follows parliamentary debates on live TV broadcasts.