BAGHDAD — An Iraqi delegation that traveled to Iran to confront it with allegations of involvement in Iraqi violence said Saturday it had secured an agreement to "stabilize security" and improve cooperation.

The statements, made upon the delegation's return Saturday night, were in stark contrast to the harsh words Iraqi officials had last week for Iran. They included allegations that Iranian-made weapons with manufacture dates of 2008 had been found in the southern city of Basra in the wake of recent clashes between Shiite militiamen and Iraqi and U.S. security forces.

The purported finds, which have not been made public, would show that Iran had broken a commitment made to Prime Minister Nouri al-Maliki last year to stop interfering in Iraq's unrest.

U.S. military officials have portrayed the Basra caches as an "eye-opener" for Iraqi leaders and said they provided Baghdad the evidence it needed to aggressively confront Iran.

Iran denies accusations of involvement in Iraq's violence. A spokesman for Iran's Foreign Ministry, Mohammad Ali Hosseini, said in an interview last week that Iran welcomed the delegation "and wants to stop the violence in Iraq."

Sheik Khalid Attiya, the deputy speaker of Iraq's Parliament, said the five-member delegation "sensed a positive stance" from Iranian officials. "The two sides have agreed to keep up efforts to stabilize security," he said.

Attiya made no mention of the recent accusations by the government, which the Pentagon has been leveling for years. U.S. military and political officials have been more vocal about the allegations since late last month, when al-Maliki launched the Basra offensive.

The United States blames much of the fighting since the offensive on Iranian-backed extremists. Iran says the United States is using it as a scapegoat for its problems in Iraq.

The heightened tensions have squeezed Iraq into an uncomfortable position as it is pressured by the U.S. to be more aggressive toward Iran, with whom it shares a long border and has strong economic ties. The powerful Supreme Islamic Iraqi Council, Iraq's main Shiite political group, is allied with al-Maliki's Dawa Party and with the United States, but it also has close ties to Iran.

The group's chief adviser in Iran, Sayyid Mohsen Hakim, refused to discuss the allegations against Iran during an interview Saturday.

But he expressed support for al-Maliki's decision to crack down on militias and repeated the prime minister's insistence that the crackdown is not targeting the Mahdi Army of Shiite cleric Muqtada al-Sadr. Al-Sadr's militia is vying for power and influence with SIIC and its Badr Organization armed wing, and al-Sadr says the crackdown is aimed at crushing his movement to give SIIC the edge in October provincial elections.

In the latest violence Saturday, the U.S. military sent a guided missile slamming into a building in the heart of Sadr City, the cleric's Baghdad stronghold. The military said the building was a command center used by militiamen to coordinate attacks on U.S. and Iraqi soldiers and civilians.

But it was next to the parking lot of a hospital, and hospital officials said at least 28 people were injured and 11 ambulances damaged in debris sent flying by the blast.

Separately, the U.S. military said late Saturday that four Marines were killed on Thursday by a roadside bomb in Anbar province. The military also said a U.S. soldier died of wounds suffered in a roadside bomb that struck the soldier's vehicle during a combat patrol in eastern Baghdad on Friday.