A leading Iraqi Shia cleric demanded on Friday that the United States sack its ambassador, accusing Zalmay Khalilzad of siding with his fellow Sunni Muslims in the sectarian conflict gripping the country. In a sermon read out at mosques for Friday prayers, Ayatollah Mohammed al-Yacoubi said Washington had underestimated the bloody conflict between Shias and the once dominant Sunni Arab minority, which many fear threatens to trigger a civil war. “By this, they are either misled by reports, which lack objectivity and credibility, submitted to the United States by their sectarian ambassador to Iraq ... or they are denying this fact,” Yacoubi said in the message, later issued as a statement. “It (the United States) should not yield to terrorist blackmail and should not be deluded or misled by spiteful sectarians. It should replace its ambassador to Iraq if it wants to protect itself from further failures.” After the imam of Baghdad’s Rahman mosque read that line, worshippers chanted “Allahu Akbar” -