Yemeni anti-terrorism forces on Tuesday killed 20 rebels and arrested 25 others in northern Yemen. The ruling People's Congress party's website said the the Houthi rebles were killed in a military operation known as the head-butt. <br/><br/>Eyewitnesses said that rebels mounted house-to-house in the northern old city of Sada to escape the attacks of anti- terrorism forces and stormed houses looking for shelters. Reports said counter- terrorism forces are pressing ahead with combing some resistance pockets in the city to clean it up of rebels.<br/><br/>Yemeni troops launched the Operation Head-butt on Sunday declaring it the last phase in the crackdown against Shiite rebels known as Houthis in Old Saada.