China's urban population exceeds rural for first time ever

Just over 680 million now live in cities – 51.27 per cent of China's entire population of nearly 1.35 billion.

Most have moved during two decades of boom in search of economic opportunities, and the historic mass migration from fields to office and apartment blocks ends the country's centuries-long agrarian status.

But the rapid modernisation and demand for improved living standards is piling extra pressure on society and the already blighted environment, experts claim.

With 75 per cent of Chinese expected to be living in cities within 20 years, the demand for more transport, energy, water and other vital infrastructure is set to test resources and city planners.

"Urbanisation is an irreversible process ... It will have a huge impact on China's environment, and on social and economic development," Li Jianmin, head of the Institute of Population and Development Research at Nankai University told reporters.

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In the 12 months from December 2010 to December 2011, a further 21 million arrived in cities – more than the population of Sri Lanka – while rural inhabitants dropped, the statistics show.

Many of those settling down in urban areas are migrant workers – people moving from the country to cities to seek economic empowerment.

This transient population of cheap labour, put at nearly 221 million by a national census last April, helped turn China into the world's second-largest economy in just three decades.

Months following the consensus, another government report said more than 100 million farmers would move to cities by 2020.

The influx is seen as having a destabilising effect on urban society, according to experts.

Government policy has failed to keep up with what some observers call the economic and social reality.

Most migrant workers are treated as lower-class citizens in their adopted towns or cities because they are still classified as rural residents under the controversial – and to many, outdated – Hukou household registration system.

The Hukou is the registration paper or residency permit which ties a migrant worker to his or her home town. This means they can only receive benefits back in their home town, and not in the cities where they go for work.

This means they have little or no social security, including access to education for their children, health and other welfare provisions.

However, expectations are growing – especially among young migrant workers who are demanding higher wagers and living standards similar to their middle class neighbours.

Worryingly for Beijing, this perceived urban apartheid is a main source of social unrest.

Also fanning discontent is what some view as a vicious circle drawn by flawed government planning, official corruption and lack of social justice because of a questionable legal system.

Many migrant workers are forced to settle in the cities because their farms have been sold off during land grabs to make way for more urbanisation.

Peng Xizhe, Professor of Demography at Fudan University, told The Daily Telegraph opinion is divided over whether to expand existing big cities or build new, smaller urban zones.

"We've been arguing for three decades about how best to implement urbanisation. In the years ahead, intelligent, smaller scale city planning will be crucial to better manage resources," he said.

"The government also realises this is important if it is to avoid polarisation among residents," he added.

Gridlocked Beijing and Shanghai, which have a combined population of over 45 million, are planning to contain the increase of their populations.

But policy is inconsistent, with other metropolises encouraging migration.

Official figures show the rate of urbanisation has gathered pace over the past decades.

Only one in five people lived in cities in 1982.

By 1990, urban dwellers represented 26 per cent of the total population – a figure that rose to 36 per cent in 2000 and jumped faster over the next decade to reach 51.27 per cent.