Prime Minister Nouri al-Maliki told an Iranian envoy Sunday that the persistent attacks in Iraq are also a threat abroad, a pointed warning amid U.S. accusations that the government in Tehran is stoking the violence by supporting Shiite militias.

Al-Maliki met with top Iranian envoy Ali Larijani in Baghdad as Iran agreed to attend a major U.S.-backed regional conference on Iraq set for this week in Egypt, raising hopes that bringing Iraq's neighbors together will help stabilize the country.

"Terrorist operations targeting Iraq will affect all countries in the world that are supposed to be supporting the Iraqi government in its war against terrorism," al-Maliki said in a statement issued by his office, adding that the prime minister also thanked Iran for agreeing to participate in this week's conference in Sharm el-Sheik.

Larijani said that "countries that want security and stability in the region have no choice but to support Iraq's elected government."

Iran has considerable influence among Shiite parties in Iraq, who now lead the country's government. It is alleged to have links with Shiite militant groups, which is why numerous American politicians and analysts have urged Washington to engage Iran in talks designed to curb the violence in Iraq.

U.S. Secretary of State Condoleezza Rice said she would not rule out the possibility of a bilateral meeting with Iran at the gathering in Egypt but stressed the focus would stay on Iraq. The Americans have refused to hold one-on-one talks over Iran's disputed nuclear program.

"Well, I think we all know that if in fact everybody believes a secure Iraq is important, then we need to stop the flow of foreign fighters," she said on CNN's "Late Edition."

"A stable Iraq is one in which its neighbors are doing the things that they need to do to help the Iraqis deal with the violent people who are trying to destabilize them, not to encourage and support those violent people."

Iraq has found itself in a difficult position since the U.S.-led invasion in 2003, with the government trying to maintain good relations with its predominantly Shiite neighbor while not angering the Americans.

The Iranian Foreign Ministry spokesman Mohammad Ali Hosseini said earlier Sunday that Larijani would raise "some questions and ambiguities about the agenda" in his talks with the Iraqi government.

He wasn't more specific.

The Iranian government has demanded the release of five Iranian officials detained in the northern Iraqi city of Irbil by U.S. troops in January, but Hosseini denied his country had linked its participation at the conference to that demand.

Rice also insisted there was no deal made regarding the detained Iranians in exchange for Iran's participation.

"There was no guarantee. We've talked to the Iraqi government and informed them that the detainees will be dealt with in the normal course," she said.

Iran says the official were diplomats who should not have been detained. The U.S. military has said the Iranians are suspected of links to a network supplying arms to Iraqi insurgents — an accusation that Iran has denied.

The head of the Iranian parliamentary committee on national security and foreign policy, Alaeddin Boroojerdi, also said Iran's failure to participate in Sharm el-Sheik would lay the Islamic republic open to criticism from the United States.

"Iran should attend the conference, actively and powerfully," Boroojerdi was quoted as saying by Iran's official Islamic Republic News Agency.

Separately, Britain said one of its soldiers was shot to death Sunday while on patrol in southern Iraq. The death brings to 146 the number of British troops killed in Iraq since the 2003 invasion — 12 of them this month.

In Baghdad, U.S. forces fired an artillery barrage in southern Baghdad Sunday morning, rocking the capital with loud explosions.

The size and the pattern of the explosions, which began after 9 a.m. and lasted for at least 15 minutes, suggested they were directed at Sunni militant neighborhoods along the city's southern rim. Such blasts have been heard in the evenings but are rare at that time of day.

In a brief statement to The Associated Press, the U.S. military said it fired the artillery from a forward operating base near Iraq's Rasheed military base southeast of Baghdad, but provided no other details.

Iraqis in the southern region of the city said American and Iraqi forces had stepped up their operations in the Dora area of southern Baghdad starting Saturday night.

Elsewhere in Iraq, the death toll from a suicide car bomb attack in the Shiite holy city of Karbala rose to 68 as residents dug through the debris of heavily damaged shops.

American troops also detained 72 suspected insurgents and seized nitric acid and other bomb-making materials during raids on Sunday targeting Al Qaeda in Iraq in Anbar province, a Sunni insurgent stronghold west of the capital, and Salahuddin province, a volatile Sunni area northwest of the capital, the U.S. military said.