Violent clashes continued for a second day Wednesday between Iraqi troops and members of an Iranian opposition group whose camp the Iraqis...

BAGHDAD — Violent clashes continued for a second day Wednesday between Iraqi troops and members of an Iranian opposition group whose camp the Iraqis stormed Tuesday, presenting the first major dilemma for the U.S. government since Iraq proclaimed its sovereignty a month ago.

At least eight Iranians have been killed and 400 wounded since Tuesday, when hundreds of Iraqi police and soldiers in riot gear plowed into Camp Ashraf, northeast of Baghdad, using Humvees donated by the U.S. military, according to group leaders and Abdul Nasir al-Mahdawi, the governor of Diyala province.

The fighting at the Iranian exile camp 60 miles north of Baghdad illustrated the shifting balance of power in Iraq as the Americans increasingly turn over responsibility to Iraqi security forces. Government forces were trying to seize control of the camp, which the U.S. had protected since 2003.

Camp residents described the day’s events as a massacre and the aftermath as a tense stalemate.

Behzad Saffari, a leader of the Mujaheddin-e Khalq, or MEK, said Iraqi troops were preventing gravely injured people from being taken to hospitals outside the group’s camp and residents feared soldiers would storm their living quarters.

The raid, ordered by Prime Minister Nouri al-Maliki, coincided with an unannounced visit by Defense Secretary Robert Gates, who left Iraq on Wednesday.

In Washington, Secretary of State Hillary Rodham Clinton described the raid as a legitimate act by a sovereign nation.

U.S. officials are deeply concerned about the reports of violence and have been monitoring the situation using camera-equipped unmanned aircraft since Tuesday, said an official who spoke on the condition of anonymity. A contingent of U.S. soldiers based outside Ashraf has been monitoring the situation but has declined to intervene, residents said.

The raid and its aftermath represent a conundrum for U.S. officials.

Some say they feel obligated to the MEK because its members have provided information about Iran’s nuclear program and because U.S. officials vowed to protect them after the 2003 invasion of Iraq.

But condemning this week’s events could be seen as an affront to al-Maliki’s government just as U.S. officials are talking up Iraq’s sovereignty, proclaimed June 30 when U.S. troops withdrew from cities.

Iranian officials have pressured Baghdad for years to expel the MEK, which seeks to overthrow Iran’s Islamic regime. But Iraq has held off from raiding the camp because the U.S. opposed a takeover.