Freelance writer Jill Carroll is shown in this file photo

Iraqi insurgents have threatened to kill a kidnapped U.S. journalist unless female prisoners in Iraq are released within 72 hours.

The kidnappers made the threat in a new videotape shown Tuesday by Arab satellite broadcaster al-Jazeera.

The tape also showed the journalist, Jill Carroll, speaking, but her voice could not be heard.

Gunmen seized Carroll and killed her Iraqi interpreter in an attack in Baghdad earlier this month.

In Washington, a State Department spokesman said officials are making every effort to secure Carroll's release.

Meanwhile, gunmen in the northern Iraqi city of Kirkuk killed at least one person in an attack on the offices of a Kurdish group.

And Iraq's military called on Iran to release nine coast guard sailors seized in a dispute on the Shatt al-Arab waterway.