China's official Xinhua News Agency announced on Thursday that the court had decided Gao was qualified to temporarily serve her sentence outside prison because of "severe illnesses."

The Third Intermediate Court of Beijing said the decision to allow Gao to serve her sentence in open custody had been based on a personal application presented on the basis of a medical certificate.

"Her family is likely to pick her up tonight from the police station," Gao's lawyer Mo Shaoping told the DPA news agency. Another of Gao's lawyers told the AP news agency that the release had been expected, but that its swiftness "came as a suprise."

Gao, who was detained last year on charges of leaking documents to the media, pleaded guilty on Tuesday, although her legal team continued to argue her innocence. She was sentenced to seven years imprisonment, later reduced to five years, with admissions of guilt often seen as meriting leniency.

Gao, who wrote hard-hitting reports of elite politics in China and worked for Deutsche Welle (DW) as a freelancer, was detained in April 2014 and jailed in April 2015 for seven years for allegedly leaking state secrets.

"When someone has been released on medical parole, they remain at risk of being re-incarcerated when the conditions of parole are no longer met, which in the case of a political prisoner like Gao Yu usually serves as a tool of control. In other words there is no commutation of punishment," Eva Pils, an expert on Chinese law at King's College London, told DW. "Also, I would expect the authorities to monitor her closely."

'Dangers' of democracy

Gao was accused of leaking a Communist Party directive that had warned of the "dangers" of multiparty democracy to a Hong Kong media outlet.

Her detention subsequently prompted a call from the US government that she be released immediately and a EU demand that China "review" her trial. Fifteen international human rights and press freedom groups - as well as DW - have long called for her immediate release.

Gao was convicted of leaking the directive - known as Document No. 9 - to an overseas news site, Mingjing News. The site has said Gao did not provide the document, with her lawyers also arguing that she was not the source of the report.

Gao was also imprisoned on state secrets charges for more than a year after the 1989 crackdown against the Tiananmen pro-democracy activists.

rc/kms (AP, dpa)