An audio tape purportedly of top al Qaeda official, Ayman al-Zawahri warned the United States yesterday it would pay a high price if it harmed any of the detainees at Guantanamo Bay in Cuba.

The voice on the tape, broadcast by the Dubai-based Arabic television Al Arabiya, also told the United States that the ?real battle? against it has not started yet.

?America has announced it will start putting on trial in front of military tribunals the Muslim detainees at Guantanamo and might sentence them to death...,? said the voice, which Al Arabiya television identified as Zawahri?s. ?I swear in the name of God that the crusader America will pay a dear price for any harm it inflicts on any of the Muslim detainees....?

It was the first audio tape said to be by Zawahri ? considered to be Osama bin Laden?s right-hand man ? since May 2 when another tape sent to an Arabic television also made threats against the United States. Al Arabiya television gave no other details about the tape.

?We tell America only one thing. What you have suffered until now is only the initial skirmishes. The real battle has not started yet,? the voice said. ?Let those who conspire with America know that America is incapable of protecting itself (...) and let every captive held by the infidels be assured that the day of liberation is soon...,? it added.

US President George W. Bush vowed last Wednesday to thwart what he said was a ?real threat? of new al Qaeda attacks and the Homeland Security Department recently warned the airline industry that al Qaeda was planning new suicide hijackings and bombings in the United States or abroad.

Washington blames bin Laden?s al Qaeda network for the September 11, 2001, hijacked plane attacks on the United States. The United States is holding more than 600 people from 42 nations as prisoners at the special camp at the Guantanamo Bay naval base.