China is mulling changes to its one-child policy, a former family planning official said, with government advisory bodies drafting proposals in the face of a rapidly ageing society in the world's most populous nation.

Proposed changes would allow for urban couples to have a second child, even if one of the parents is themselves not an only child, the China Daily cited Zhang Weiqing, the former head of the National Population and Family Planning Commission, as saying on Wednesday.

Under current rules, urban couples are permitted a second child if both parents do not have siblings. Looser restrictions on rural couples mean many have more than one child.

Population scholars have cited mounting demographic challenges in their calls for reform of the strict policy, introduced in 1979 to limit births in China, which now has 1.34bn people.

'Gradual change'

Zhang said the commission and other population research institutes have submitted policy recommendations to the government.

Zhang, who now serves on China's congressional advisory body, said any changes if adopted would be gradual.

"China's population policy has always taken into account demographic changes but any fine-tuning to the policy should be gradual and consider the situation in different areas," China Daily cited Zhang as saying.

The relaxed policy might be implemented first in "economically productive regions" and places that have followed closely existing regulations, the paper said.

Demographers warned that the one-child policy has led to a rapidly greying population that could hamper China's future economic competitiveness.

Critics said it also has fuelled forced abortions and increased social tensions stemming from an imbalance in the number of boys and girls born.

Though forced abortions are illegal in China, officials have long been known to compel women to have the procedures to meet birth-rate targets.

Family planning debate

Earlier this year, debate over the country's strict family planning rules erupted after a woman in the northwestern province of Shaanxi was forced by officials to abort her seven-month pregnancy.

The one-child policy of the 1980s has given rise to a phenomenon known as 4-2-1. The only child having to look after not only his parents, but two sets of grandparents.

"Filial piety is an ancient Chinese tradition and today many young adults still say it would be shameful not to have their parents at home with them," Al Jazeera's Laura Kyle said.

By 2050, it is predicted that a third of the population - some 450 million people - will be aged 60-plus.

"But in a country that’s developing at breakneck speed, sons and daughters in their twenties and thirties are focused on work – getting their share of China's growing wealth," she added.