Friends of a man arrested in China over an anti-government Twitter posting have told Sky News they have now lost contact with the man's wife.
Zhai Xiaobing, who writes on Twitter under the handle @Stariver, was arrested by Beijing police in the suburb of Miyun on November 7 and held at a local police station.
It is understood Mr Zhai was arrested because of a tweet he had posted three days before his arrest. The tweet is said to have offended the ruling Communist Party during their once-in-a-decade power transition.
Speaking by telephone to Sky News, a close friend said he was very worried for Mr Zhai and his wife.
"We don't know what's going on inside there with him. Now we have even lost contact with his wife," the friend, who asked not to be named, said.
"I have told the police that if they want to investigate those around him, talk to me, not his family."
Examination of Mr Zhai's Twitter account, which is still active, shows a number of tweets which refer to the 18th National Congress of the Communist Party. The congress ended last week with the secretive selection of new leaders.
The tweet, which his friends believe incriminated him, reads: "The Great Hall suddenly collapsed, more than 2,000 people attending the meeting, only seven escaped, but then all died one after another mysteriously.
"Is it God's game? Or the angry fire of the death? How could the mysterious number of 18 opens the door of hell? 8 Nov, global theatres, shockingly releasing."
The 'Great Hall' refers to the Great Hall of the People where the party congress was held. The numbers he refers to correlate with several facts about the Congress.
Two thousand delegates attended the Congress and the number of men selected for the top jobs was reduced from nine to seven, the Congress was the 18th to be held and began on November 8.
Mr Zhai is understood to be being held at Beijing’s Miyun Detention Centre. Police at the centre, contacted by Sky News, refused to comment on the matter.
However, Sky News has obtained some further details about Mr Zhai's arrest from other sources.
It is understood he was arrested on November 7 - the day before the Communist Party Congress began.
He was alone at his Beijing home when the police arrived. His wife then received a phone call at 2am the following morning. She went to the police station and was shown a certificate detailing his arrest.
The certificate claimed he had been arrested for 'spreading rumours of terrorist information'. She was refused access to him. Under Chinese law, applications can be made by family and lawyers to see detained people, but the authorities have the right to refuse all access.
A photo, obtained by Sky News, shows Mr Zhai with dissident Chinese artist Ai Wei Wei who is constantly clashing with the Chinese authorities. Mr Zhai and Mr Ai are said to know each other.
Mr Zhai’s friend, who agreed to speak to Sky News by phone, described him as a "regular, ordinary person".
He was born in 1976, graduated from Beijing University and works in the finance industry. He is said to have "no particular political background whatsoever".
"He is lively, thinks a lot, likes to make jokes and has liberal views." the friend said.
Twitter is banned in China. The vast majority of the population have no access to it because of a nationwide firewall. Nicknamed the 'great-fire-wall of China', it blocks access to Twitter, Facebook, YouTube and international versions of Google's search engine.
It is possible to bypass the firewall with the use of a Virtual Private Network (VPN). It is likely this is what Mr Zhai was using to access the site.
A domestic version of Twitter, called Weibo, is available although it is monitored and key words are blocked.
Just before the Communist Party Congress, known dissidents were put under close supervision under house arrest or ordered to leave Beijing. Their restrictions were lifted at the end of the congress.
It is not clear why Mr Zhai would be detained and held for so long for that single tweet.
However, other tweets in his timeline refer to the purged Communist Party official Bo Xilai. Mr Bo is currently awaiting trial for corruption. His wife was convicted of murdering British businessman Neil Heywood.
Mr Zhai's tweets appear to suggest that he is a supporter of Mr Bo, a fact that might also explain why he has been detained.
A growing online petition is calling for his release.