NAJAF, Iraq (Reuters) - U.S. troops have attacked Shi'ite militia forces around the Iraqi holy city of Najaf, seizing the local governor's offices and killing 41 fighters, a senior official in the U.S. occupation authority has told Reuters. Reuters correspondents at the scene on Thursday saw and heard fierce battles in and around Najaf and the nearby town of Kufa. One saw U.S. tanks at the governor's building on Najaf's main street, several kilometres (miles) from Shi'ite Islam's holiest shrines. It was the boldest move yet against an insurgency launched a month ago...