A court in Iran has sentenced a French man to eight years in jail on spying charges, his Paris-based lawyer said Tuesday, denouncing his trial as a sham and the accusations as baseless.

Benjamin Briere, 36, who was arrested in May 2020 while travelling in Iran and is currently on hunger strike, was also given an additional eight-month sentence for propaganda against Iran's Islamic system, his lawyer Philippe Valent said in a statement. 

"This verdict is the result of a purely political process that is... devoid of any basis," he said.

Slamming the trial, which began on Thursday, as a "masquerade", he added that Briere "did not have a fair trial in front of impartial judges" and noted he had not been allowed to access the full indictment against him.

Briere is one of more than a dozen Western citizens held in Iran, described as hostages by activists who say they are innocent of any crime and detained at the behest of the powerful Revolutionary Guards to extract concessions from the West.

Nationals of all three European powers involved in the talks on the Iranian nuclear programme -- Britain, France and Germany -- are among the foreigners being held.

"It is not tolerable that Benjamin Briere is being held a hostage to negotiations by a regime which keeps a French citizen arbitrarily detained merely to use him as currency in an exchange," Valent added.

He said Briere was "more and more weakened" by a hunger strike that has now lasted a month.