A court run by Yemen's Houthi rebels on Tuesday sentenced 30 academics, trade unionists and preachers to death for allegedly spying for the Saudi-led coalition, a judicial source said.
The men, among 36 defendants tried by the criminal court in the rebel-held capital Sanaa, have been in custody for at least the past year, the source told AFP.
"The criminal court today (Tuesday) issued a verdict condemning 30 people to death on charges of spying for the aggression countries," the source said, adding that the other six were acquitted.
He said the men were convicted of supplying the coalition with information on locations for air strikes.
Amnesty International condemned the verdicts, saying they had targeted "political opposition figures" in "sham trials".
Among those condemned to death was Yussef al-Bawab, a 45-year-old father of five and linguistics professor, who had been "arbitrarily arrested in late 2016", it said in a statement.
"Since the Houthi de facto authorities assumed control of the justice system in 2015, they have progressively utilised the Sanaa-based SCC (Specialised Criminal Court) to target persons they deem to be opponents or even just critics," said Lynn Maalouf, Amnesty's Middle East research director.
The military coalition intervened in Yemen in March 2015, a few months after the Iran-aligned Shiite Houthi rebels captured Sanaa.
The coalition backs the internationally-recognised government of President Abedrabbo Mansour Hadi.
Since the Houthis took control of the capital in September 2014, their courts have issued several death sentences for spying.
In May last year, a Sanaa court sentenced two men to death for spying for Riyadh, while in January, the same court condemned to death 22-year old mother Asmaa al-Omeissy and two men on charges of aiding the United Arab Emirates, a key partner in the coalition.
On Tuesday, the supreme court commuted Omeissy's death penalty to 15 years in jail, a judicial source in Sanaa said. There was no decision yet on the two men sentenced with her.
Yemen's conflict has killed tens of thousands of people, many of them civilians, relief agencies say, and left millions displaced and in need of aid.