China artist Ai Weiwei 'banned from using Twitter'
Chinese artist and government critic Ai Weiwei is reported to be under further restrictions following his release after nearly three months' detention.
Mr Ai has already said he cannot talk to the media, and he is not allowed to leave Beijing without permission.
He is also reportedly banned from using the microblogging site Twitter. His account has been dormant since April.
Mr Ai was released from detention on Wednesday after the authorities said he had confessed to tax evasion.
China's foreign ministry has outlined the terms of Mr Ai's bail, which are valid for 12 months, saying that Mr Ai is not allowed to leave Beijing without permission.
Mr Ai has made it clear to the media that he is unable to discuss his case.
Now it appears he cannot tweet either.
Mr Ai regularly used social networking sites to keep in touch with his fans and followers. He has more than 89,000 followers on Twitter and has tweeted more than 60,000 times - the last time was on 3 April, the day he was detained.
Some lawyers have expressed disquiet about these restrictions.
One pointed out that no formal charges have been brought against the 54-year-old. The restrictions show, he says, the extensive legal powers enjoyed by the Chinese authorities.
China's police allege Mr Ai has admitted to tax evasion and promised to pay back the money. But no more details have been given.
Mr Ai's arrest in April sparked an international outcry.
He was held for 80 days at a secret detention centre with no access to a lawyer or contact with his family.
Western governments had demanded Mr Ai's release and that of many other activists who have been rounded up by China's authorities in recent months, in what is the most serious crackdown on dissidents in China in many years.
The artist's case is expected to come up during Chinese Premier Wen Jiabao's European tour. Mr Wen is currently in Hungary, and will travel to the UK and Germany.
The state-run Global Times newspaper on Friday published an article saying that Mr Ai's release was not a result of Western pressure.
"Western media believe foreign pressures have worked. It seems that their interpretation will do no harm to China's external relations," it said.
"But China will hold its judicial sovereignty in its own hands. The country will continue to stride forward, and it will not pay heed toward this inane chatter.
"Ai Weiwei, like the rest of his countrymen, will keep living his life within the framework of Chinese laws."