Wu Hongfei was detained Monday by Beijing police on the charge of "causing trouble," likely because of a post on her microblog, said Hu Jia, an activist who is friends with Wu.
Last weekend, Wu wrote on her microblog that she would like to blow up government housing commission offices. In the post since removed by censors, Wu berated those who work for the agency.
The post was made shortly after a man set off a bomb at Beijing's airport, a blast that injured no one but the accused bomber.
Beijing police did not respond to a request to verify Wu's detention.
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Chinese authorities have been known to arrest, convict and jail those who make bomb threats on charges of spreading terrorist rumours.
New York-based Human Rights Watch said it is likely Wu's detention was political retribution for her past criticisms of the government.
Hu said Wu has been targeted because the authorities want to deter further discussions of Ji Zhongxing, the 33-year-old man accused of setting off the homemade bomb at Beijing Capital International Airport on Saturday. Ji's brother says the man suffered a beating in 2005 that left him paralysed from the waist down and had grown frustrated after years of unsuccessfully trying to seek redress.
Hu said authorities have singled out the singer, Wu, partly because she has been outspoken against social ills in the past. She has a relatively strong following on social media with nearly 120,000 followers on her microblog hosted by Sina Weibo, a Twitter-like service.