COPENHAGEN: A Danish terrorism expert on Thursday questioned the authenticity of a taped message attributed to al-Qaeda which threatened Norway, saying the speaker meant Denmark but made a mistake.

Osama bin Laden's top lieutenant, Ayman Al-Zawahiri, on Wednesday called on Muslims to carry out more suicide attacks against Western targets, citing Norway alongside the United States, Britain and Australia, in a taped message attributed to him. Terrorism expert Lars Erslev Andersen said he believed the audiotape "was not authentic", saying the speaker meant to name Denmark, a staunch US ally in the war on Iraq along with Britain and Australia.

Andersen said Al-Zawahiri would never have confused the two Scandinavian countries, casting doubt on the identity of the speaker. "I think he (the speaker) must be thinking of Denmark or Poland, which participated in the war on Iraq, and not Norway, which did not take part," he said.

"I think it is a mistake," he said, adding: "Al-Zawahiri knows these two countries well. Confusing them this way can only indicate that it is the voice of someone else on the al-Qaeda tape."

Al-Zawahiri is known to have visited Denmark many times in connection with his role as editor, until 1996, of the Islamic newsletter "Al Moujahidoun" which is published in Copenhagen.

However, he never lived in Denmark, Islamic sources in the country said. Norwegian officials have meanwhile expressed surprise at finding their country on the list of al-Qaeda targets.

Following the message and possible confusion over Denmark and Norway, Copenhagen police stepped up security around foreign embassies, including those of the United States, Britain and Israel which are considered potential targets.