BEIJING — Chinese police have detained two rights activists who worked for a prominent nongovernmental organization (NGO), their relatives said on Monday, the latest sign of an intensifying clampdown on the work of nonprofit groups. About half a dozen security officials from the central city of Zhengzhou took Yang Zhanqing, previously an office director of Yirenping, from his home in the southern city of Huizhou late last Friday, said his wife, surnamed Bu. She declined to give her full name. Bu said her husband had been criminally detained on a charge of “illegal business activity.” Police also detained Guo Bin, who was also an Yirenping office director who fought against discrimination of people with disabilities, into custody late on Friday on the same charge, said Guo's girlfriend surnamed Wang, who declined to give her full name. Wang said Guo was taken from a hospital in the southern city of Shenzhen where his son was undergoing an operation. The Ministry of Public Security did not respond to a request for comment. Calls to Zhengzhou police went unanswered. Chinese Foreign Ministry spokesman Lu Kang said he was not aware of the case. The charge of “illegal business activity” has been used recently against many NGO representatives. In April, police charged the legal representative and administrative director of Transition Institute, a think-tank that researches business, business regulations, reform and civil society, with “illegal business activity.” “It appears that the greatest likelihood is that authorities are pressing false charges against him,” Bu said, referring to Yang, who advocated for the rights of Hepatitis B carriers. — Reuters