Al-Jazeera television has aired what it says is an audiotape from Osama bin Laden's top aide, in which he urges Muslims to attack Western targets in Muslim lands.
The Qatar-based satellite channel says the speaker on the tape is Ayman al-Zawahri, the number two man in the al-Qaida terrorist network.
The speaker calls on Muslims to attack the embassies and commercial interests of four countries -- the United States, Britain, Australia and Norway. He urges Muslims to follow the example of hijackers who carried out the September 11th (2001) attacks in New York City and Washington.
The United States blames Osama bin Laden and al-Qaida for those attacks, which killed about three-thousand people.
US State Department spokesman Richard Boucher says US officials have lodged protests with both the government of Qatar and al-Jazeera executives over the airing of the tape.
Mr. Boucher says the tape is, in his words, a series of calls to commit horrible acts against innocent people. He says the decision to air it was "irresponsible."
There has been no confirmation the voice on the tape is actually Ayman al-Zawahri. Al-Jazeera did not disclose how or when it obtained the audiotape.
Meanwhile, Saudi security officials say three suspected al-Qaida members arrested earlier this week were planning to attack landmarks in the country using a hijacked airliner. Officials say the three men -- all Moroccans -- were arrested at an airport in the city of Jeddah on Monday. They say the suspects are part of a larger al-Qaida cell at work in the Saudi kingdom.
Four countries, including the United States and Britain, have temporarily closed their embassies in the Saudi capital, Riyadh, because of heightened fears of a terror attack.
The closures come nine days after multiple suicide bombings in the Saudi capital, Riyadh, killed 34 people, eight of them Americans. Saudi authorities blame al-Qaida for those attacks.