More than 10 percent of Japanese people have crossed 80 years or older for the first time, new official data showed, as the nation faces a rapidly greying population.

Government data released on Sunday, ahead of Monday's "Respect for Aged Day" national holiday, also showed that the share of Japan's population at 65 or older expanded to a record 29.1 percent from 29.0 percent a year ago.

The level compared with second-ranked Italy's 24.5 percent and third-ranked Finland's 23.6 percent, according to the internal affairs ministry.

"Japan has the highest percentage of elderly population in the world," the ministry said in a press release.

For decades, Japan has seen its population shrink and grow older as young people delay marriage and children largely due to unstable jobs and economic difficulties.

As a result, Japan has seen ballooning costs for elderly care with not enough young people to fill jobs and pay for various social and welfare programmes.

The ministry said that with the baby boomer population turning 75 or older, Japan's 124.4 million people are continuing to grow older.

Around 12.59 million people are 80 or older while 20 million are 75 or older, it said.

As a result, Japan is relying on an elderly labor force.

More than nine million elderly are working, accounting for 13.6 percent of the workforce, or one in seven workers in Japan.

A quarter of all elderly in Japan have jobs, less than South Korea's 36.2 percent, but far ahead of other developing countries such as the United States at 18.6 percent, and France at 3.9 percent.

More than a third of people between 70 to 74 have jobs in Japan, the data showed.

By 2040, Japan's elderly population is projected to account for 34.8 percent of the population.