Baghdad, Iraq ? Iraq’s most influential Shiite cleric on Saturday warned the prime minister to quell violence or risk “other powers” filling the gap, while police found the tortured and blindfolded bodies of 13 Pakistani and Indian pilgrims and their Iraqi driver.

At least 15 violent deaths were reported elsewhere in Iraq, while the government announced it had formally taken over the notorious Abu Ghraib prison from coalition authorities.

Prime Minister Nouri al-Maliki met with Grand Ayatollah Ali al-Sistani in Najaf, 100 miles south of Baghdad, the cleric’s office said. In July, al-Sistani was credited with restraining the Shiite community from widespread retaliation against minority Sunnis following horrific attacks on Shiite civilians.