The size of China's workforce may decline by as much as 23 percent by 2050, a government official said, as the population of the world's second-largest economy rapidly ages.

China's working age population, defined as those between the ages of 16 and 59, peaked in 2011 and would soon "experience a process of sharp decline", particularly after 2030, said Li Zhong, a spokesman for the Ministry of Human Resources and Social Security, at a news conference.

He forecast that last year's tally of 911 million people of working age could fall as low as 700 million by 2050 -- a decline of over 23 percent.

"Over the long term, macro-level data analysis shows that we must focus on the development of human resources as a whole, and study how to more fully and more efficiently make use of labour resources," he said Friday.

China is faced with deep demographic challenges, thanks in large part to decades of the strict and at times brutal enforcement of its hugely controversial "one child" policy.

The country now has 220 million people over the age of 60, Li said, accounting for over 16 percent of its total population.

China's economy grew by 6.9 percent last year, its slowest rate in a quarter of a century, and its shrinking workforce has heightened the challenges brought on by sluggish economic growth.

The country has drafted plans currently pending approval to delay retirement age, with Li stating that the decision would have "limited" impact on employment for younger people.