Unless Thailand comes up with comprehensive urban plans, Bangkok and other major cities will turn into "uncontrollable, toxic anthills" like a number of cities around the developing world, warned a leading demography expert yesterday.

Starting from next year, the world is entering the "dawn of an urban millennium" in which more than half of the world's population is projected to be living in urban areas, according to the State of the World Population 2007 launched yesterday by the United Nations Population Fund (UNFPA).

Urbanisation is defined by the UN report as "the increase in urban share of the population" and normally entails concentrations of poverty, slum growth and social disruption.

The trend is particularly true in the developing world, which will make up 80 per cent of urban humanity by 2030.

"While the world's urban population grew very rapidly [from 220 million to 2.8 billion] over the 20th century, the next few decades will see an unprecedented scale of urban growth in the developing world," the report stated.

"This will be particularly notable in Africa and Asia where urban populations will double between 2000 and 2030 ... the accumulated urban growth of these two regions during the whole span of history will be duplicated in a single generation."

The fact that half of Thailand's 65 million people are now living in urban areas is no surprise given the "urban-bias, rural neglected" policy of the country since the beginning of the development era in the 1960s, said Kritaya Archavanitkul, director of Mahidol University's Popula-tion and Social Research Institute.

"Thailand's economic growth is based on a continuous withdrawal of natural resources from rural areas," she said.

"Hydropower dams, for example, have deprived rural people of their resources to feed industrialisation and urbanisation," Kritaya added.

The demographic expert suggested that Thailand is in need of real urban plans that take into account the balanced development of the entire country to stop a massive migration of people from the rural sectors flocking into cities for jobs.

"Climate change will also add insult to injury with increasing heat, floods and pollution," she said. "We never have any real plans that take future problems into account."

Thailand's rapid urbanisation is a cause of alarm and Kritaya's institute will organise a conference to address several dimensions of the problem on Friday.

A representative from UNFPA will make a presentation of its new population report.