Yemen's Houthi group arrested a number of people in Sanaa on Saturday, following demonstrations over economic hardship.
Sanaa residents told Reuters dozens were arrested, including 16 female students.
The students were released at the end of the day after signing a pledge not to take part in demonstrations again, one of them said, asking not to be identified for fear of retribution.
She said female Houthi supporters "attacked us with electric shock batons and clubs, supported by armed men".
"They beat me until I fell to the ground and I received an electric shock in the back when I stood up again. I wasn't able to move when they took me to the police station," she said.
The Iran-aligned Houthis took control of Sanaa in 2014, ousting the internationally-recognised government of Abd-Rabbu Mansour Hadi. A Saudi-led military coalition intervened in 2015 to restore it.
"Security services in the capital detained a number of mercenaries tasked by the aggressors to plant rumours and disturb public peace," the Houthi-controlled Saba news agency said.
Both sides of the Yemen conflict have been accused of serious human rights violations.
Soaring prices have put some basic commodities out of reach for many Yemenis and the central bank has struggled to pay public-sector salaries, on which many depend, as foreign exchange reserves dwindle.