One of the most outspoken critics of the Chinese government, Hu Jia, has been released from prison.

Mr Hu, 37, has spent the last 42 months in prison after being found guilty in 2007 of “incitement to subvert state power”.

His imprisonment followed his appearance before a European Parliament committee where he spoke about the human rights situation in China. He had also criticised the Chinese authorities in several articles and interviews with the media.

In one open letter in 2007, Mr Hu wrote: “The Olympics will be held in a country where there are no elections, no freedom of religion … where torture and discrimination are supported by a sophisticated system of secret police.”

News of his release was announced by his wife, Zeng Jinyan, after his prison term came to an end on Sunday.

In a Twitter post, she said her husband had been released at 0230 local time on Sunday.

“We are fine and happy. Need to rest for some time. Thank you everyone,” the post read.

As police stand guard outside Mr Hu’s Beijing home, a BBC correspondent said it appeared that Mr Hu had been put under some form of house arrest and had been banned from speaking to the media.

Days before Mr Hu’s release, the US-based Human Rights Watch urged the Chinese government not to place him under house arrest.

The agency’s Asia advocacy director, Sophie Richardson said: “Hu Jia should never have been imprisoned in the first place.

“If that injustice is compounded by another form of detention it will show just how shallow the Chinese government’s ‘rule of law’ commitments are.”

His release comes one week after that of artist Ai Weiwei, whose imprisonment sparked international outcry and a worldwide campaign calling for his release.