Sheikh Hassan bin Abdullah al-Ahmar said the latest batch of soldiers released had been held by the Huthi rebels in the region of Al-Amishiya in northern Amran province.

"They have arrived in my home town of Amran and are my guests," said Sheikh Hassan, a pro-government prominent tribal chief who helped to mediate the prisoners' release.

He said the rebels promised to free another 128 soldiers "tomorrow or the day after."

On Wednesday, the Shiite rebels let go 200 soldiers they had captured two days earlier and promised to release other prisoners, both civilian and military, in the coming days.

The rebels and the army engaged in deadly fighting in July that lasted nine days, rattling an already fragile truce agreed in February which had ended a six-month round of fighting in a conflict that started in 2004.