BAGHDAD, Iraq — Prime Minister Nouri al-Maliki met with Iraq's most influential Shiite cleric Saturday to discuss the country's deteriorating security situation, while attacks killed 13 Pakistani and Indian pilgrims south of the capital and three bombings left six people dead.

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.

The meeting came two days after a barrage of coordinated attacks across mainly Shiite eastern Baghdad killed 64 people and wounded 286. Hundreds of Iraqis have been killed in violence this week, despite a massive security operation in the capital involving an extra 12,000 Iraqi and U.S. troops that has targeted some of Baghdad's most problematic neighborhoods.

On Friday, the Defense Ministry said security forces would expand the crackdown in a week to 10 days to the eastern parts of the capital, including Shiite militia strongholds.

Separately, authorities postponed a highly anticipated ceremony Saturday in which the Defense Ministry was to assume operational control of the country's armed forces from the U.S.-led coalition. The ceremony was postponed until Sunday.

Coalition spokesman Lt. Col. Barry Johnson said the reason was "miscommunication" in the timing of the ceremony.

Iraq's Defense Ministry and Joint Headquarters were to assume responsibility for the Iraqi Ground Forces Command, the Iraqi Air Force and the Iraqi Navy, U.S. authorities had said. Handing over control from the coalition to Iraqi authorities is a key part of any eventual drawdown of U.S. troops in the country.

In Washington on Friday, the U.S. Defense Department issued a report to Congress saying sectarian violence is spreading in Iraq, with illegal militias becoming more entrenched, especially in Baghdad neighborhoods where they are seen as providers of security and basic social services.