Blind activist Chen Guangcheng challenged China's central government Wednesday to prove that it had not ordered his illegal house arrest, and to punish those who turned his home into a prison.

The 40-year-old legal campaigner spent two years in illegal house arrest after serving a four-year jail sentence on charges related to his work exposing forced sterilisations and abortions under China's population control policy.

After his dramatic escape and flight to the US embassy, he released a video detailing the abuses he suffered at the hands of local officials in his home province of Shandong in eastern China.

Since then, government officials have visited him in hospital four times and have pledged to look into his allegations, he said, challenging them to follow through with the investigation.

"The central government needs to prove they were not behind my treatment in Shandong," Chen told AFP in a phone interview from the Beijing hospital where he has been since he left the US embassy a week ago.

"I told them if they did not investigate (the illegal house arrest), then everyone will believe that they ordered it.

"If they go down and punish those in Shandong, then people will believe that this was the doing of officials in Shandong."

Chen has been a symbol of China's dismal human rights record since his 2006 conviction, with the United States and the European Union loudly condemning his treatment.

Since his release from jail in 2010, up to 100 security guards had surrounded Chen's home in Dongshigu village 24 hours a day, preventing him and his wife from leaving their home and preventing outsiders from seeing him.

No legal explanation for his house arrest was ever announced by the local government in Shandong.

Chen's supporters -- including Hollywood actor Christian Bale -- as well as foreign and domestic journalists were routinely attacked by the security guards if they approached the village.

Chen and his wife were also beaten last year when he smuggled out a video that detailed the climate of fear they were enduring.

"For two years they treated me brutally, coming into the home to threaten and beat us," Chen said.

"For two years they did not allow me any outside communication. I could not see friends, they didn't let me read newspapers, they even confiscated our television and radio."

Chen's case sparked a diplomatic crisis with Washington and has made headlines around the world, but there has been relatively little coverage of his case in China's state-run media.

On Wednesday, the Global Times daily said in a commentary that overseas forces were using him as a political tool to demonise China.

"External forces would like to use this to politicise and universalise some of China's social conflicts," it said in an article that appeared only in the paper's English-language edition, which has a mainly foreign readership.

"They want Chen's case to become deadlocked, drawing in international attention and becoming an issue as big as what has happened in Libya and Syria, so that they can capitalise on this opportunity to demonise China as a whole."

Chen's escape from the heavily guarded home last month became a major diplomatic affair after he sought refuge in the US embassy in Beijing days ahead of a visit by US Secretary of State Hillary Clinton.

He spent six days in the embassy before being taken to a Beijing hospital under a deal between the Chinese and US governments.

He has since said he fears for his and his family's safety in China and wants to leave for the United States, where he has been offered fellowships to study law. China has said he can apply to leave the country for study abroad.