The detainees were being held in cramped offices in the small rural town of Puning in southern Guangdong Province, the Nanfang Countryside Daily reported.
Chinese family planning authorities ordered the detentions as part of a campaign to sterilize 10,000 men and women suspected of attempting to violate the country's strict limits on the size of families, The Times of London reported.
Puning said it launched the 20-day campaign April 7 after many couples left their homes for factory jobs and exceeded the limits on family size, the Nanfang newspaper said.
As part of the campaign, parents of those who refuse voluntary sterilization or try to elude authorities have been detained, the newspaper said.
Those being held included the 64-year-old father of Huang Ruifeng, who has three daughters. "Several days ago, a village official called me and asked me or my wife to return for the surgery. Otherwise, they would take away my father," Huang told the Chinese daily.
In Puning and most other rural areas of China, farmers are allowed to have a second child if the first is a daughter, but no more.
Extreme enforcement of the limits in China had been on the decline after decades of reported abuses dating to the 1970s, including forced later-term abortions, sterilizations and even the killing of newborn babies, the Times noted.
An official at the Puning Population and Family Planning Bureau told the Global Times, "It's not uncommon for family planning authorities to adopt some tough tactics."