Yemen's internationally-backed government on Wednesday threatened to suspend prisoner swap negotiations with the Houthi rebels in protest against death sentences handed to 30 detainees in Sanaa.

"The death sentences issued by the illegitimate Houthi court against 36 political activists in Sanaa are considered illegal," said Hadi Haig, head of the prisoner swap committee, on Twitter.

"The Houthi actions may lead to suspending the negotiations of implementing the prisoner swap deal or a complete collapse," he warned.

Meanwhile, the Yemeni government official also called on the UN envoy to "stand against these illegal Houthi actions."

On Tuesday, a court in the Yemeni rebel-held capital Sanaa sentenced 30 people to death over charges of espionage for Saudi Arabia and its allies in the anti-Houthi military coalition fighting the Houthi rebels in Yemen.

These people, mainly academics, professors and students who are members of the Al-Islah, a Yemeni political party linked to the Muslim Brotherhood, were arrested during a Houthi security campaign in 2016.

Amnesty International, a London-based non-governmental organization focused on human rights, condemned the trial as a "mockery of justice," urging the Houthis to immediately release the 30 men.

Saudi Arabia has been leading an Arab military coalition against the Iran-allied Houthi rebels in Yemen for more than four years in support of the exiled internationally recognized government of Yemeni President Abd-Rabbu Mansour Hadi.