Government troops began house-to-house searches for al-Qaida in Iraq militants in Mosul on Thursday, part of a major security operation to cleanse Iraq's third largest city from cells of the terror network. Prime Minister Nouri al-Maliki flew to Mosul on Wednesday to take charge of the operation by US-backed Iraqi forces. Described by the US military as the last major urban base of al-Qaida in Iraq, Mosul has become the site of al-Maliki's third security drive in two months as he attempts to defeat Shiite militants and Sunni extremists. Al-Qaida, however, appears to be far from defeated. In an attack that bore the group's hallmarks, a suicide bomber Wednesday blew himself up in a funeral tent in a village west of Baghdad, killing 22 people and wounding 40, according to police Col. Faisal al-Zubaie. The funeral for Taha Obaid, a primary school principal killed the previous day by gunmen, was attended by local, US-backed Sunni tribesmen fighting al-Qaida militants. It was not known how many of them were among the killed and wounded. A three-year-old son of Obaid was among those killed, said al-Zubaie.