Norway, South Korea tightens security

The alert was raised from low to moderate, Joern Holme, head of Norway's anti-terrorism services, said in a communique.

"When Norway is threatened so directly there is every reason to take the threat seriously," he said, cautioning that Zawahiri was a key al-Qaeda chief who could influence other groups.

Security has been tightened around South Korean interests overseas after a new al-Qaeda threat against countries supporting the US-led coalition in Iraq, government officials said Saturday.