Hundreds of people in a southern China city, mostly senior citizens, have been confined in dozens of government-owned offices and kept from leaving until their sons or daughters who have violated the nation's family planning policy agreed to accept sterilization.

Those elderly people were taken from home by family planning staff in Puning City of Guangdong Province to be "concentrated for class," a local newspaper quoted a Puning family planning official as saying.

By Sunday, 1,377 people in Puning had been taken to the offices, the Nanfang Rural News reported yesterday.

At one of Puning's townships, nearly 100 people, including babies, were forced to crowd into a 200-square-meter room watched by three unidentified men, the newspaper said.

Without space to lie down, some had to stand or squat. They breathed filthy air in the damp room and had to huddle in the cold because of a shortage of quilts, said the newspaper.

They were taken to the room because their sons or daughters, working out of town, bore too many children.

Local officials called those migrants home for sterilization, threatening to take their families away if they refused.

Some migrants tried to play for time because of their uncompleted effort for a son, but most came back immediately for the surgery so that their families could be released.

Puning, a city of 2.2 million people, was often criticized by Guangdong family planners for performing poorly on population control.

Local officials said that they had no choice but to take harsh measures, while the city's family planning bureau chief blamed local people's traditional idea for more children, especially boys.