BAGHDAD (Reuters) - Three U.S. soldiers were charged with the rape and murder of an Iraqi teenager and killing her family, bringing to four the number of Americans accused of the four deaths in March, the U.S. military said on Sunday.

A fourth soldier was charged on Saturday with dereliction of duty for failing to report the case.

Last week a fifth soldier, Steven Green, who has now left the army, was charged with rape and murder in a U.S. civilian court over the killings at Mahmudiya, near Baghdad.

The case, one of several serious accusations against U.S. troops in Iraq in recent weeks, has outraged many Iraqis and prompted some to call for American forces to leave.

Prime Minister Nuri al-Maliki called for a review of U.S. troops' immunity from prosecution under Iraqi law.

In U.S. federal court documents, prosecutors said Green went with three other soldiers from the checkpoint they were manning to a nearby house where Green killed two adults and their younger daughter before raping and killing the other girl.

A second soldier also took part in the rape, other soldiers involved alleged. The two other soldiers who went into the house told prosecutors they did not kill or rape anyone.

A fifth soldier in the unit said he was aware of the crime committed after the other four had been drinking and talking about rape but that he had not reported it afterwards.