A US private security officer in Iraq  (18 Sept. 2003 file photo)

The United Nations is urging the United States to ensure that American private contractors who commit offenses in Iraq are prosecuted.

The U.N. Assistance Mission to Iraq is making the call in its new report on the human rights situation in that country Thursday. The mission noted several fatal incidents involving private security firms in the period between April and June of this year.

The report calls on the U.S. to establish mechanisms to hold contractors accountable when such incidents do not appear to be justified.

Iraqi authorities are outraged over two recent deadly shootings involving private security firms. Seventeen Iraqi civilians died when guards with Blackwater USA opened fire on a Baghdad street.

And two Iraqi women were killed on Tuesday by guards employed by an Australian-owned company.

The Associated Press is reporting that the U.S. State Department may phase out or limit the use of private security guards in Iraq, a move which could end Blackwater USA's tenure in that country.

Some information for this report was provided by AFP, AP and Reuters.