He said the case was referred to the Iraqi judiciary.

Iraq’s president, meanwhile, demanded that the Americans release an Iranian arrested this week on suspicion of smuggling weapons to Shi’ite militias. The demand adds new strains to US-Iraqi relations only days before a meeting between President Bush and Iraq’s Prime Minister Nouri al-Maliki. Interior Ministry spokesman Maj Gen Abdul-Karim Khalaf said Iraqi authorities had completed an investigation into the September 16 shooting in Nisoor Square in western Baghdad and concluded that Blackwater guards were responsible for the deaths.

He said that the conclusion was based on witness statements as well as videotape shot by cameras at the nearby headquarters of the national police command. He said eight people were killed at the scene and three of the 15 wounded died in hospitals. Blackwater, which provides most of the security for US diplomats and civilian officials in Iraq, has insisted that its guards came under fire from armed insurgents and shot back only to defend themselves.

Blackwater spokeswoman Anne Tyrrell said on Saturday that she knew nothing about the videotape and was contractually prohibited from discussing details of the shooting.

Government spokesman Ali al-Dabbagh denied that authorities had decided to file charges against the Blackwater guards and said Saturday that no decision had been taken whether to seek punishment.

“The necessary measures will be taken that will preserve the honor of the Iraqi people,” he said in New York, where al-Maliki arrived Friday for the UN General Assembly session. “We have ongoing high-level meetings with the US side about this issue.”

‘Security vacuum’
Meanwhile an Iraqi official conceded on Sunday that Blackwater USA’s exit would create a “security vacuum” in Baghdad and said US and Iraqi officials were instead working on revamping regulations governing private security companies after a deadly shooting of civilians. Following the September 16 Nisoor Square shooting, the Interior Ministry banned Blackwater from operating in Iraq but rolled back after the US agreed to a joint investigation. The company resumed guarding a reduced number of US convoys on Friday.

But officials said new rules have to be put in place to govern the behavior of the security companies.“If we expel this company immediately, there will be a security vacuum that will demand pulling some troops off the battlefield,” said Tahseen Sheikhly, a civilian spokesman for the seven-month-old offensive against militants in Baghdad and surrounding areas.

“This will create a security imbalance in securing Baghdad.”

He said a joint US-Iraqi committee was studying the framework of operations for private security companies who have largely operated without oversight since the war began in March 2003.