Security guards from a private US military contractor involved in a shooting incident in Iraq have been granted immunity by State Department investigators, a news report said Monday.

According to the report by the New York Times' online edition, the guards employed by the Blackwater Company to protect State Department officials in Iraq gained the limited-use immunity during an inquiry by the department's investigative arm, the Bureau of Diplomatic Security (BDS).

Citing unidentified officials close to the investigation, the report said that prosecutors at the Justice Department, instead of BDS investigators, have authority to grant such immunity, but they had no advance knowledge of the BDS arrangement.

Limited-use immunity, as officials explained to the newspaper, means that security guards were promised they would not be prosecuted for anything they said in their interviews with the authorities as long as their statements were true.

The State Department and the Justice Department both did not comment on the matter, while the company's spokeswoman Anne E. Tyrell told the newspaper "it would be inappropriate for me to comment on the investigation."

The Federal Bureau of Investigation took over the case from the State Department on Oct. 3 and has since then begun to re-interview Blackwater employees without granting any immunity to assemble independent evidence of possible wrongdoing.

The Justice Department is currently considering whether any prosecutions could take place involving US civilians in Iraq following the Blackwater shooting incident, the report said.

Blackwater is a major military contractor providing security services to the US government in Iraq. Its guards opened fire in a crowded Baghdad square when protecting a State Department convoy, killing as many as 17 Iraqi civilians on September 16.

Some government officials told the newspaper that granting immunity was a potentially serious investigative misstep that could complicate efforts to prosecute the company's employees involved in the incident.

Blackwater employees and other civilian contractors can not be tried in US military courts or in Iraq courts and it is unclear what US criminal laws might cover criminal acts committed in a war zone, the report said.

According to the Coalition Provision Authority (CPA), a law issued by a former US administrator in Iraq Paul Bremer, the "multinational forces, foreign liaison missions, their personnel, property, funds and all international consultants shall be immune from the Iraqi legal process."

However, the enraged Iraqi government said Tuesday it would revoke the immunity of foreign security firms from being prosecuted granted by the CPA.

Earlier this month, the House of Representatives overwhelmingly passed a bill that would make contractors like Blackwater liable under a law known as the Military Extraterritorial Jurisdiction Act.

(Xinhua News Agency October 30, 2007)