BAGHDAD (AP) – Iraq’s most influential Shiite cleric has “concerns” about the U.S.-Iraqi security pact, but will leave voters to decide its fate in a referendum to be held by July 30, an official at the cleric’s office said Saturday.

The comments by Grand Ayatollah Ali al-Sistani were made public two days after parliament approved the deal which would allow American troops to stay in Iraq through 2011.

In what may have been a reaction to the security deal, a rocket slammed into the Green Zone near a U.N. compound Saturday, killing two foreigners and wounding 15 people.

An official at al-Sistani’s office said the Iranian-born cleric did not think the pact had won national consensus, something he thought “may lead to instability in the country.” He also viewed as vague parts of the agreement, particularly those pertaining to judicial jurisdiction and controls over the exit and entry into Iraq by American troops, according to the official, who spoke on condition of anonymity because of the sensitivity of the subject.

Al-Sistani also believed that the pact did not offer sufficient guarantees to restore Iraq’s full sovereignty, according to the official.

Al-Sistani, said the official, “will leave the acceptance or rejection of the agreement to the Iraqi people through the referendum” expected by July 30, the official said. The three-member presidential council must approve the deal, too.

If the agreement is rejected by voters, Iraq’s government would have to either re-negotiate it with the Americans or drop it altogether. Putting the agreement to a vote was one of several concessions made by the government to mostly Sunni lawmakers in exchange for their support for the pact.

Al-Sistani enjoys enormous support among Iraq’s majority Shiites and could have buried the agreement had he publicly spoken against it before Thursday’s parliamentary vote.

The comments attributed to him Saturday, however, clearly show that he was unhappy about the margin of support it had won in Thursday vote.

Just under 200 of the legislature’s 275 lawmakers attended the voting session. Of these, about 150 voted in support of the agreement.

The agreement gives a clear timeline for a U.S. withdrawal from Iraq, from the cities by June 30 and the entire country by Jan. 1, 2012. It gives Iraq a strict oversight over their movements and operations and limited jurisdiction in the case of serious crimes committed by U.S. soldiers and civilian Pentagon employees when off-base and off-duty.

The Green Zone attack occurred as followers of anti-U.S. Shiite leader Muqtada al-Sadr hoisted black flags on houses, mosques and Sadrist offices in their Baghdad stronghold to protest the U.S.-Iraqi pact. Tech. Sgt. Chris Stagner, a U.S. military spokesman, said explosives ordinance teams had determined Iranian-made rockets were used in the Green Zone attack as well as another strike late Friday against Camp Victory, the main military headquarters on the western outskirts of the Iraqi capital. That attack caused only minor damage, Stagner said.

The rocket fell near the compound about 6:15 a.m., the United Nations said in a statement. It was the first such strike in more than a month against the Green Zone, a sprawling area in central Baghdad that also houses the U.S. Embassy and the Iraqi government headquarters.

Rocket and mortar strikes against the U.S.-protected Green Zone have been common throughout the war but recently tapered off after a Shiite militia cease-fire that followed weeks of fighting with U.S. and Iraqi troops last May.

The U.N. declined to provide identities or nationalities pending notification of relatives, but it said no Iraqi or international U.N. staff members were among the casualties. The dead worked for a catering company, the U.N. said. The U.N. presence in Iraq has been limited since the organization’s Baghdad headquarters was bombed in Aug. 2003, killing 22 people, including top U.N. envoy Sergio Vieira de Mello.

The U.S. military accuses Iran of providing weapons, funding and training to Shiite extremists that oppose the U.S. presence in Iraq. Iran has consistently denied the charge.

The U.S. military also announced that a roadside bomb attack Friday damaged a U.S. mine-resistant, ambush-protected vehicle, known as the MRAP, in the Sadrist stronghold of Sadr City. Three men suspected in connection with the attack were detained, the military said. Iraqi security forces also intensified their presence in previously set up checkpoints at Sadr City’s main entrances.