China's two-child policy is showing “notable results” with the fertility rate expected to rise through to 2020, a senior health official said on Saturday.

Speaking to reporters on the sidelines of China's annual meeting of parliament, Wang Peian, vice-minister of the National Health and Family Planning Commission said there were “notable results” in 2016, with the largest annual number of newborn babies since 2000.

Wang said 18.46 million live births were recorded last year, two million more than the average of the previous five years.

The total fertility rate also rose to 1.7 children per woman, compared to 1.5-1.6 between 2000 and 2015, he added.

China introduced the controversial “one-child policy” in the 1970s to limit population growth, but authorities are now concerned the country's dwindling workforce will not be able to support an increasingly ageing population.

In 2015, China said it would allow all married couples to have two children, to address those concerns. Wang said the rising trend will continue through to 2020, during which the annual number of newborns is expected to range between 17m and 19m.

“We are very optimistic,” he added.

China's birth rate, one of the world's lowest, was considered an achievement by the government, which was concerned about over-population, but has since become a source of anxiety for authorities worried about an ageing workforce.