BAGHDAD, Iraq – Iraq’s most feared terror leader called on his followers yesterday to show patience and prepare for a long struggle against the Americans, promising in an audiotape posted on the Internet that “ferocious wars … take their time” but victory was assured.

Elsewhere, American troops launched fresh raids around the northern city of Mosul, killing five suspected insurgents, in a bid to rein in guerrillas and safeguard the January 30 national elections. Iraqi forces sealed off main routes into Baghdad a day after a wave of deadly car bombings.

The 90-minute message, purportedly from Abu Musab al-Zarqawi, appeared to be aimed at rallying his forces following the loss of their base in Fallujah and at marshaling support as Iraqis prepare for their first poll since the collapse of Saddam Hussein’s regime.

“Fighters who have taken the path of jihad have to realize the nature and the demands of the battle toward the required goal,” the speaker said. “This group has to be patient in the path that it has taken and…not to hurry victory. The promise of God will be fulfilled no matter what.”

The authenticity of the tape could not immediately be verified. It appeared before President Bush was sworn in for a second term that begins under the shadow of a continuing insurgency in Iraq.

The speaker also acknowledged that a leading Al Qaeda commander in Fallujah, Omar Hadid, had been killed fighting the Americans when the city fell to an American-Iraqi assault. Hadid was believed to have escaped the fighting.

“Ferocious wars are not determined by the outcome of days or weeks,” the speaker on the tape said. “They take their time until it’s time to announce the victory of one of the parties.”

Mr. al-Zarqawi is the leader of an Al Qaeda affiliate that was responsible for kidnapping and beheading several foreigners, including Americans, before the fall of their Fallujah base. America has offered a $25 million reward for Mr. al-Zarqawi’s capture or death – the same amount as for Osama bin Laden.

In a separate statement, Mr. al-Zarqawi’s group claimed responsibility for an explosion yesterday that injured five British soldiers and an undetermined number of Iraqis at a supply base in southern Iraq outside Basra. A Web statement said the attack was a suicide operation in retaliation for alleged British abuse of Iraqi prisoners.

The authenticity of that statement also could not be determined, and the British military gave no reason for the blast. Three British soldiers are on tri al at a British base in Germany for allegedly abusing Iraqi prisoners in May 2003.

In the audiotape, Mr. al-Zarqawi also denounced Iraqi Shiites for fighting alongside American troops – an apparent attempt to inflame sectarian tensions ahead of the vote.

The elections have been embraced by majority Shiites but rejected by many minority Sunnis, who say it should be postponed because of the violence.