When the head of family planning in Shanghai said young couples should have more babies because the city was growing old, it sounded like a statement of the obvious.

Yet within days there was a storm of comment on the internet and in state media as people asked whether this meant the government was preparing to relax its one-child policy.

There are signs officials are rethinking the ban, which has prevented 400 million births since 1979, because on present trends China’s population will begin to decline by the middle of the century. By then, India will have overtaken it as the most populous nation.

Xie Lingli, the Shanghai family planning official, was forced to explain publicly that he had not deviated from the party line, which restricts most couples in Chinese cities to one child.

The rules allow couples who are both only-children to have two babies. Shanghai has introduced other exceptions, including more leeway for fishermen and farmers. It has also abolished a rule that couples who are allowed more than one child must wait four years between births.

“There’s a huge social demand for second children,” said Yang Henmin, an engineer in Shanghai. “In the end the government cannot control it any more than it can grasp the wind.”

The city’s family planners talk of “encouraging” more births in a change of tone that sounds distinctly like liberalization by stealth.

“In the past we stressed birth control, not the chance to have a second child. Not many people know these exceptions to the regulations so we were just reminding them,” said Xie.

There are few babies to be seen on the streets of China’s commercial capital. The city is ageing so quickly that by 2020 more than a third of its 19 million people will be 60 or over. The city’s pension fund faces bankruptcy.

Click here for the full report from the London Times.