Migrants are fuelling a baby boom, with officials warning birth rates may outstrip the city's resources.

Guangzhou, one of the economic powerhouses of South China, is currently home to more than 3.6 million migrants.

Sources with the Guangzhou Population and Family Planning Bureau said migrant births in the city totalled 79,812 last year, an increase of 7.9 per cent over 2005.

Migrants are people who live legally in the city but are registered elsewhere.

"The growing migrant population is the main cause for the increasing number of births, Duan Jianhua, an official with the bureau, told China Daily yesterday.

"If measures to curb the rising birth rates within migrant families are not taken, the city will experience a population explosion," said Duan.

Zhu Xiaodan, Party secretary for Guangzhou, said at a work meeting last week that the city currently has a population of nearly 12 million, including migrant people and those with permanent residence certificates.

The city, with an area of 7,434 square kilometers, is only able to host 15 million people, Zhu said.

"With the increasing number of migrants, we will see a sharp decrease in available natural resources in the near future," Zhu said.

Meanwhile, Zhu said the number of babies born in the surrounding rural areas had also risen in recent years.

"People in rural areas have not changed their views on childbirth, leading to an unbalanced gender birthrate," Zhu said.

Zhu called for further promotion of family planning knowledge among rural families.

"In addition, we will strengthen management efforts for migrant people, and build a system to record migrants' information in terms of employment, living standards and family planning, in a bid to better control the rising birthrate," said Zhu.

Editor: Yan