BAGHDAD (AP) – Mortar shells slammed into an Interior Ministry prison on Monday, killing at least seven inmates and wounding 23, police and a hospital official said. One of Iraq’s main refineries came under fire in a separate attack in the capital, the latest strike against an oil industry vital to the country’s economic recovery.

Iraq’s foreign minister, meanwhile, said a new security pact with the United States would set a time limit on the American troop presence, saying the government’s eventual goal was “to reach a level of preparedness that leaves us with absolutely no need for foreign forces to remain in the country.”

The mortar rounds hit a prison made up of several cell blocks, each containing prisoners accused of terrorism-related crimes or civil offenses, police said.

Police said American troops sealed off the area and were investigating the 6:30 a.m. bombardment. The U.S. military said it had no immediate information, and Iraqi Interior Ministry officials could not be reached for comment.

A hospital official said the inmates were sleeping when the mortars hit, one landing directly on a cell and two others nearby. Casualties were sent to a hospital inside the Interior Ministry compound for treatment, the official said.

In Baghdad’s Dora neighborhood, a rocket or a mortar shell hit one of Iraq’s three main oil refineries, police and an Oil Ministry spokesman said. The U.S. military confirmed an attack in the area.

Assim Jihad, a spokesman for Iraq’s Oil Ministry, said a rocket or mortar shell landed on a storage tank. He said no casualties were reported and the plant was still operating. “The fire is under control and within a few hours it will be extinguished. This will not affect production,” Jihad told The Associated Press. A police official said the fire was caused by a 120 mm mortar round.

The police and hospital officials spoke on condition of anonymity because they were not authorized to release details of the attacks.

Iraq’s oil industry has come under repeated attack since the war began, including on Friday when a bomb exploded beneath a key pipeline outside the northern city of Beiji, home to the country’s largest refinery.

According to Oil Ministry figures from July, the industry suffered 159 attacks in 2006 by insurgents and saboteurs, killing and wounding dozens of employees and reducing exports by some 400,000 barrels a day. Such attacks have cost Iraq billions of dollars since the 2003 U.S. invasion.

Iraqi Foreign Minister Hoshyar Zebari said Iraq had formally requested U.N. authorization for the U.S.-led presence in Iraq.

“We left an underline that the Iraqi government hoped that this would be the last extension of the mandate,” he said, adding the negotiations for a new pact with the Americans would be “the most important that Iraq has ever entered.” He said the deadline for reaching an agreement was July: “There will be negotiations about the conduct of these (U.S.) troops and their rights, privileges and also questions of command and control.”

Zebari also said U.S. and Iranian experts would meet Dec. 18 to discuss security issues ahead of an expected round of formal talks on Iraq’s stability. He said both sides agreed to a fourth round of ambassador-level talks in Baghdad, but the timing was under discussion.

Previous sessions ended inconclusively with Iran rejecting U.S. allegations that it supports Shiite insurgent groups in Iraq by providing bomb-making materials responsible for the deaths of American troops.

Zebari’s comments came a day after Iraq’s national security adviser, Mouwaffak al-Rubaie, warned Washington that a strategy of aligning its Sunni Gulf allies against Iran would only exacerbate tensions in the region. “The United States, until they seriously engage with Iran… the long-term regional security will be in doubt,” al-Rubaie said on Sunday, the final day of a regional security summit in the Bahraini capital Manama.

Violence has declined sharply in Iraq since June, when the influx of American troops to the capital and its surrounding areas began to gain momentum. Baghdad has seen some of the most dramatic improvements, but deadly attacks persist throughout the country.

On Monday, a roadside bomb targeting a police patrol in eastern Baghdad killed one policeman and injured five other people, police and hospital officials said. And on Sunday, in a Shiite region about 60 miles (100 kilometers) south of Baghdad, a roadside bomb struck a convoy carrying a popular police chief with a reputation for leading crackdowns against militias and resisting pressure from religious and political groups to release favored members. The death Sunday of Brig. Gen. Qais al-Maamouri, the police chief of Babil’s provincial capital of Hillah, was the latest in a series of assassinations against provincial leaders in the mainly Shiite region.

Hundreds marched along dusty roads in Babil to mourn al-Maamouri, chanting and firing guns into the air. The office of Iraqi President Jalal Talabani said in a statement that “Iraq has lost a good son and a bold military commander.”

At least two Islamic militant Web sites on Monday called al-Maamouri a brutal, anti-militant figure and broadcast old audio clips of the slain al-Qaida in Iraq leader Abu Musab al-Zarqawi describing him as “God’s enemy.” “We swear to God that no one like him can remain alive,” said al-Zarqawi, who was killed in a U.S. airstrike in 2006.