(Adds clashes in the area) BAGHDAD, Jan 17 (Reuters) - Several explosions which police sources said were mortar rounds went off on Wednesday in the Haifa Street area of central Baghdad, where U.S. and Iraqi forces staged a major offensive against Sunni rebels last week. There were no details on casualties. Police said there were fierce clashes in the area after the mortars hit and the fighting was still continuing. Iraqi and U.S. forces launched a major operation to reassert their control over the area last week, describing it as riddled with "terrorist hideouts". Dozens were arrested including people described by the Iraqi government as foreign Arab fighters. Iraqi soldiers have maintained a stepped up presence in the area since then, with checkpoints and patrols. More than 100 people were killed in last week's violence in Haifa Street, a mainly Sunni Arab area in central Baghdad.
