Iraqi police say a female suicide bomber has killed at least 19 people and wounded at least 40 - the latest in a series of attacks on Shi'ite pilgrims heading to a major religious festival south of Baghdad.

Police say the woman detonated her explosives Thursday in Iskandariya, as the pilgrims set off for the festival in the Shi'ite holy city of Karbala.

Earlier, in Baghdad's Karrada district, police say a roadside bomb killed another pilgrim and wounded at least seven others as they headed to the festival.

Also today, police say an explosion killed a policeman in the capital's southern Zafaraniya district.  Security officials say the blast wounded at least five other people.

Tens of thousands of Shi'ites are expected in Karbala for the festival marking the birth of Imam al-Mahdi, Shi'ite Islam's 12th and last imam.

In other news, the U.S. Navy today accused six sailors of abusing detainees at a U.S. detention center in Iraq in May.

The Navy says the sailors were working at a camp in southern Iraq when the alleged assaults took place.  It says two detainees suffered minor abrasions and eight others were sealed in a cell that had been sprayed with a "riot control agent."

A Navy statement says the six sailors face courts martial.  Seven other sailors received non-judicial punishments in the incident.

In other violence today, officials say a roadside bomb killed two policemen and wounded six others when it struck their patrol near the Iraqi town of Buhriz, north of the capital.

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