Militants linked to wanted terrorist Abu Musab al-Zarqawi have threatened to kill three Western hostages unless the United States releases female prisoners from two Iraqi jails within 48 hours.

In a video broadcast Saturday on Arabic television channel al-Jazeera, the two American and one British hostage are shown blindfolded and sitting on the floor with a hooded gunman standing behind them.

The kidnappers demand the release of women held at Abu Ghraib prison near Baghdad and Umm al-Qasr jail in southern Iraq.

The authenticity of the video has not been confirmed.

The two Americans and Briton work for a Gulf-based construction company and were abducted from their Baghdad home early Thursday.