Shiite militiamen detained three journalists covering a protest in Sanaa on Sunday against the rebels' takeover of the Yemeni capital, the journalists' union said.

Union secretary general Marwan Damaj also said that female freelance journalist Huda al-Zabhani was beaten up.

Reuters photojournalist Mohammed al-Sayaghi was detained along with fellow Yemenis, Samed al-Samei of Aloula newspaper and Yahya al-Qabati of Aleshteraki.net news website, he said.

Sayaghi later told AFP that he was released after being held for an hour, during which he was questioned.

Shiite militiamen, also known as Huthis, fired warning shots to disperse the protest near Sanaa University.

On Saturday, thousands of Yemenis took to the streets of Sanaa in the biggest demonstration to date against the Huthis, who overran the capital unopposed in September.