BAGHDAD — More than 350 prisoners at U.S. military facilities in Iraq were freed over the weekend after having their cases reviewed by a joint board determining the threat they posed, U.S. military officials said Monday.

All of prisoners were male, officials said.

The kidnappers of two German engineers and an American journalist have demanded that all female prisoners in U.S. custody be released, or the two groups would kill the hostages.

After a series of videotapes last month, there has been little word about the hostages’ state.

The prisoner release is the latest in a series by the Combined Review and Release Board, made up of U.S. military officials and Iraqi government representatives. Since August 2004, when the board was established, more than 15,600 prisoners have been recommended by the board for release, U.S. officials said.

The review involves U.S. and Iraqi officials getting short briefings on each prisoner and the particulars of the cases against them. If the board agrees the prisoner no longer poses a threat to Iraqi or other security forces, they are recommended for release.

Some 14,000 prisoners are in American custody at facilities throughout Iraq.

U.S. officials have confirmed that they will hand over the notorious Abu Ghraib prison complex to Iraqi control, perhaps within the next three months.

Many of the prisoners now there will be transferred to new or refurbished U.S. facilities elsewhere.

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