Chinese activist Chen Guangcheng said Friday his nephew is facing a charge of "intentional murder" after attacking officials who broke into his home, despite the fact no one died in the encounter.

The nephew, Chen Kegui, is in detention after he attacked intruders who broke into the family home in eastern Shandong province apparently searching for his uncle following his dramatic escape from house arrest last month.

Lawyers for the nephew have said a local Communist Party official was injured seriously in the fight in the early hours of April 27 and two others were slightly injured, but no one died.

But Chen Guangcheng said police had issued an arrest warrant charging his nephew with "intentional murder" -- an assertion backed by rights lawyers who have taken up his case.

"This is outrageous, it is totally unreasonable," the blind activist told AFP by phone from the Beijing hospital where he is being treated for injuries sustained during the escape.

"Up to 10 people battered down the door and entered the home looking for me, but when they couldn't find me, they began beating people ... Chen Kegui was clubbed over the head so he picked up the knife and defended himself."

Police in Yinan county that oversees Dongshigu village, where Chen was kept under house arrest, refused to comment when contacted by AFP.

The news comes a day after Chen accused authorities in Shandong of targeting his relatives in retaliation after he escaped from under the noses of guards on April 22 and fled to the US embassy in Beijing.

Rights lawyers confirmed the murder charge, but said it was unlikely to stick because no one had been killed.

"I don't believe this kind of criminal charge will stand because Chen was only engaged in self-defence," lawyer Liu Weiguo told AFP.

"Even if it wasn't self-defence, the most they could charge him with is intentional injury, not intentional murder ... no one was killed."

Chen said the seriously wounded official, named Zhang Jian, had burst into his home up to five times during his house arrest, confiscating and breaking household belongings while never producing legal documents permitting entry.

"This Zhang Jian many times led a group of people into our home, to beat and take our belongings, there was never any legal procedures," Chen said.

Chen, 40, spent two years under extralegal house arrest after ending a four-year jail sentence in 2010 on charges related to his work exposing forced sterilisations and abortions under China's population control policy.

After leaving the US embassy he was taken to the Beijing hospital, but then decided he did not feel safe in China and wanted to leave with his wife and two children to study in the United States.

Hospital authorities and a strong security presence have kept friends, supporters, journalists and US embassy officials from visiting him, but he has been able to communicate with the outside world by phone.

Government officials last visited Chen on Monday, when they promised him they would help him process paperwork that would allow him to receive a passport and go to the United States.

Earlier they promised an investigation into his treatment in Dongshigu.