The White House has reiterated its refusal to negotiate with al-Qa'ida in the face of questions as to why Osama bin Laden remains at large.
Scott McClellan, the White House spokesman, insisted Bin Laden's ability to move and operate was being hampered by US efforts, but he was unable to explain why more than four years after George Bush declared he wanted him "dead or alive" the al-Qa'ida leader had managed to evade capture.
"He is someone who is on the run," Mr McClellan said. "We don't negotiate with terrorists. We put them out of business."
The audio tape was one of more than 30 messages that have been issued by the al-Qa'ida leader or his deputy since 11 September 2001.
Its broadcast comes just days after a US missile attack in Pakistan reportedly killed at least four senior al-Qa'ida operatives including at least a dozen civilians adding to suggestions that the US may be increasing its efforts to attack the terror group.
Bin Laden's deputy, Ayman al-Zawahiri, was the chief target of the air strike early last Friday in the remote north-eastern part of the country close to the border with Afghanistan. But the Egyptian failed to show up for a dinner which he was expected to attend.
Among the al-Qa'ida members reportedly killed in the strike was Midhat Mursi al-Sayid Umar, 52, an Egyptian claimed by the US Justice Department to be an explosives expert and poisons instructor.
He is alleged to have trained hundreds of fighters at camps in Afghanistan before the Taliban regime was ousted at the end of 2001. There was a $5m (£2.8m) reward for information leading to his arrest.
Also apparently killed was Abu Obaidah al-Masri, an al-Qa'ida operative blamed for attacks on US troops in eastern Afghanistan, and Abdul Rehman al-Maghribi, a Moroccan said to be Zawahiri's son-in-law.
Pakistani officials told the Associated Press that Maghribi was involved in public relations for al-Qa'ida.
Some officials said a fourth man, Khalid Habib, was also among the dead. He is said to be al-Qa'ida operations chief along the Afghan-Pakistan border. Officials said he was the most senior figure killed and that he had organised assassination attempts on General Pervez Musharraf, the President of Pakistan.Reuse content