An al-Qaida supporter has threatened attacks on cities in America and Australia.
Authorities say the masked man shown in a video broadcast on the ABC news network Sunday is believed to be Adam Gadahn, a U.S. citizen reportedly living in Pakistan. During the 11-minute tape, he said "Yesterday London and Madrid. Tomorrow Los Angeles and Melbourne."
Los Angeles officials say there are no known, credible threats against the city, and called the tape propaganda.
Meanwhile, al-Qaida's leader in Iraq, Abu Musab al-Zarqawi, has accused U.S. forces of using poison gas in an attack on the Iraqi city of Tal Afar. The accusation was made in an audiotape posted on the Internet and attributed to Abu Musab al-Zarqawi.
In the broadcast, the speaker also said the devastation along the U.S. Gulf Coast caused by Hurricane Katrina was the result of prayers to God.
U.S. officials say they are trying to verify the tapes, both of which apparently were timed to coincide with the fourth anniversary of the September 11, 2001 terrorist attacks on the United States.