The relatives of a Chinese activist have been seized from their homes after he was accused of writing a letter calling for the resignation of China's leader Xi Jinping. Wen Yunchao – known as "Beifeng" – says that he saw a copy of the letter on the Chinese state-controlled online news service However, he has denied any connection with either the website or the letter.

In a telephone interview Wen said that his family, who live in Jiexi, Guangdong, have been harassed by the authorities since 10 March. Wen has now received a phone call from his sister-in-law telling him his parents and brother have been detained. All three relatives were seized from their homes on 22 March.

According to reporting by Sky News, the final conversation Wen had with his father was five days previously. Wen has reportedly been told by the authorities that there would be no further adverse consequences if he revealed the identity of the writer of the letter and how it was published. He said: "Is it because Xi Jinping is facing a crisis over power control? Or does the Chinese government feel they are facing a ruling crisis? That caused the authorities to over-react."

Wen said he believes the Chinese government is confronted by a crisis, fuelled by a massive increase in social problems which have been triggered by the slowdown of the economy. He added: "For this kind of political case, there's very little a legal channel can do. The only thing I can do is to go through public awareness, international human rights agencies, and other government, in the hope of creating public pressure to push the local authorities to release my family members as soon as possible."

The activist currently lives in New York. He told Sky News that sources had told him that more than seven people working for have been seized by the authorities. Earlier in March, Chinese columnist Jia Jia was seized by Beijing police on his way to Hong Kong. Wen believes Jia's detention is part of the crackdown that has ensured after the publication of the letter. Phone calls to Jiexi police and government by British journalists have not been answered.