US Army soldiers from 1st Battalion, 502nd Infantry Regiment conduct routine patrol in Mahmoudiyah (file photo)

U.S. military officials say at least three soldiers are under investigation for allegedly raping a woman and then killing her and three family members in Iraq in March.

The investigation is the latest in a series of probes of U.S. troops allegedly killing civilians in Iraq.

In a written statement, the U.S. military Friday said a criminal investigation was launched into the alleged killing of four family members in their home in Mahmoudiya, south of Baghdad. The statement did not elaborate.

The Russian diplomatic car which was attacked in the upscale Mansour district of Baghdad, June 3, 2006

In other news, Russia announced a $10 million reward for information that leads to the killers of four embassy employees taken hostage and killed in Iraq. The head of the Federal Security Service, Nikolai Patrushev, announced the offer in Moscow.

On Sunday, the kidnappers posted an Internet video showing the killing of the four Russians.

In another development, Romanian President Traian Basescu said Romania will not pull its troops out of Iraq. Prime Minister Calin Tariceanu proposed the withdrawal Thursday because of what he said was the human and financial cost of the deployment. But President Basescu said Friday that Romania's Supreme Defense Council rejected the move.

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