Her lawyer, Mo Shaoping, said the verdict was “wrong” because the court failed to take into consideration that Gao’s confession on state television last May was coerced because of threats made against her son. He was initially detained along with her but was later released.

Mo also said that even though the prosecution produced no evidence to support its allegations that Gao used Skype software to send an internal Communist Party memo called Document No 9 to the US-based news website Mingjing in July, 2013, the court still accepted this as truth. Mingjing said on its website on Friday that the allegation was untrue; it obtained the document in June, long after it had been circulated online.

The verdict also said Gao obtained a photocopy of Document No 9 from Yao Jianfu, a retired party official and policy researcher, in June 2013 and alleged that while she knew it was state secret, she still sent an electronic version to Mingjing founder Ho Pin.

It said that although Gao denied this during the trial, the court was not convinced.

News reports said Yao had been detained but released on bail in June last year.

He could not be reached for comment yesterday.

Speaking to the South China Morning Post from New York, Ho denied that he obtained Document No 9 from Gao, saying his publication was given the circular by someone from the party's propaganda authorities in order to contest other incorrect versions circulated online. He said his publication, which has broken many exclusive reports on senior leaders, had many connections among officials and did not need to obtain a report like Document No 9 from a journalist.

Document No 9 ordered cadres to tackle seven subversive influences on society, including “Western constitutional democracy” and “universal values” such as human rights and free speech. Mo argued that the document, which gives ideological guidance to cadres, could not be seen as a “state secret”.

Another lawyer for Gao, Shang Baojun, said the verdict was disappointing and unjust.

Gao’s brother, Gao Wei, said that as his sister was led away yesterday she smiled and said: “I’ll be fine. I will appeal.”

He said he hardly recognised her because she had become so thin and her hair much greyer.

Gao Wei said that by giving Gao such a long sentence, the authorities had effectively silenced her. He was also worried that Gao, who has high blood pressure and heart disease, would not live out her jail term.

“She has been muzzled. When she is out she will be nearly 80. What can she do?” he said. “I doubt she can hold up until then.”

Gao has been detained since April 24, last year and pleaded innocent at her trial in Beijing in November.

“We call on the Chinese authorities to release Ms Gao immediately and respect China’s international human rights commitments,” a US State Department official said.

“The conviction of veteran reporter Gao Yu is part of a disturbing pattern of government action against public interest lawyers, internet activists, journalists, religious leaders and others who peacefully question official Chinese policies and actions,” he added. Gao was named one of the International Press Institute’s 50 “world press heroes” in 2000. 

Before Friday’s sentence was handed down, Gao had already spent a total of seven years in jail. She was locked up for 15 months on the eve of the Tiananmen crackdown in 1989, and was jailed again in 1993 for six years for leaking state secrets in her writing on politics.

In an interview before she was arrested last year, Gao said her experiences only spurred her to probe more deeply into her country’s affairs.

“You can change mountains and rivers but not a person’s nature – seven years in jail did nothing to dampen my enthusiasm for news,” she said.

In her 2009 book, My June 4th, published 20 years after the Tiananmen pro-democracy movement, she wrote that following the "massacre", the Communist regime wanted people “to abandon their souls to become stones in a high wall”.

“But there are still countless souls hidden inside the thin and fragile [egg] shells that are independent and irreplaceable, and they are breaking against that firm, high wall,” Gao wrote. “Twenty years on, I am still like some of those eggs, continuously breaking against that high wall.”

Amnesty International researcher William Nee condemned Gao’s jailing as “blatant political persecution” and said Gao was “the victim of vaguely worded and arbitrary state-secret laws used against activists as part of the authorities’ attack on freedom of expression”.

Maya Wang, China researcher for Human Rights Watch, said Gao’s heavy sentence “reflects the worsening crackdown on civil society since President Xi Jinping came to power”.

Veteran journalist Ching Cheong, who spent nearly three years in jail on the mainland, said Gao’s sentence reinforced the message that the authorities were firmly in charge and “people have to toe the party line closely”.

The United States urged China to free Gao, saying her jailing was "part of a disturbing pattern" of actions against those who question Beijing's policies, Agence France-Presse reported.

With additional reporting from Agence France-Presse