Islamic rebels ambushed and killed three Yemeni policemen on Tuesday in the second such attack in two days, sparking a fresh hunt for the group, Yemeni security sources said. They said six other policemen were wounded in the ambush by followers of slain anti-U.S. cleric Hussein al-Houthi in Amrah province, 100 km (62 miles) north of the capital Sanaa. On Monday, supporters of Houthi killed seven policemen and wounded 20 in an attack on a police station and an ambush in Saada province, 240 km (150 miles) north of Sanaa.Local sources said Yemeni security forces killed 10 rebels on Monday in a large operation in Saada. They said the clashes continued on Tuesday, but gave no further details. Yemeni security sources have blamed Houthi's elderly father, Sheikh Badr el-Deen, for the new round of violence. They said he had shunned a government amnesty, quit Sanaa and returned to his Saada stronghold to foment violence.