A Chinese court on Friday sentenced a 71-year-old woman journalist to seven years in jail for leaking state secrets, it said, in a case seen by rights groups as part of a crackdown on government critics.

Gao Yu -- named one of the International Press Institute's 50 "world press heroes" in 2000 -- "illegally provided state secrets to foreigners", Beijing's No. 3 Intermediate People's court said on a verified social media account.

"We are very disappointed with this verdict," said Shang Baojun, one of her lawyers who argued in court that a "confession" from Gao had been extracted after threats were made against her son.

Gao is "the victim of vaguely worded and arbitrary state-secret laws that are used against activists as part of the authorities' attack on freedom of expression," said William Nee, a researcher for Britain-based Amnesty International.

Gao went missing last April and resurfaced on China's state broadcaster a month later admitting she had made a "mistake" -- a statement used as evidence by prosecutors at her trial.

Shang said the statement was made after police made threats against the journalist's son.

He added that after the verdict was read out in court Gao had stated in a "strong voice" that she would appeal, but was not allowed to make any further statement.

China's definition of "state secrets" is notoriously broad, taking in the number of people executed each year, information about pollution, and databases listing commercial companies.

The prosecution's case against Gao was reportedly connected to the 2013 leaking of an internal Communist Party communique calling for a harsh crackdown on dissent and warning against Western-style democracy and criticism of the party's historical record.

An outspoken advocate of liberal values, Gao was imprisoned following the government crackdown on student protests in Tiananmen Square in 1989.

She was detained with dozens of other government critics in the lead-up to the crackdown's 25th anniversary last year.

Gao's political writings saw her jailed for six years in the 1990s, also on a charge of "leaking state secrets".

The US said last year it was "deeply concerned" by the criminal proceedings against her.

Ahead of the verdict, France-based Reporters Without Borders said it would be a gauge of "how far the Chinese authorities are ready to go in order to suppress those who speak with an independent voice".