Al-Qaeda leader Osama bin Laden appeared in a new message aired on an Arabic TV station Friday night, for the first time claiming direct responsibility for the 2001 attacks against the United States.

The militant Islamic group decided "we should destroy towers in America" because "we are a free people... and we want to regain the freedom of our nation," said bin Laden, dressed in yellow and white robes and videotaped against a plain brown background.

In the 18-minute message, parts of which were played on Qatar-based Al-Jazeera just four days before the American presidential election, bin Laden accused U.S. President George W. Bush of negligence on the day 19 suicide hijackers took over four American passenger jets.

He also threatened new attacks if the policies of the U.S. government do not change.

According to translators, bin Laden told American voters: "Your security is not in the hands of [Democratic presidential candidate John] Kerry or Bush or al-Qaeda. Your security is in your own hands.

"Each state that does not meddle with our security has naturally guaranteed its own security."

Bush insists U.S. 'will prevail'

Bush reacted to the tape by saying the United States would not be intimidated by bin Laden's attempt to interfere in Tuesday's election.

"Americans will not be intimidated or influenced by an enemy of our country," he said. "We're at war with these terrorists and I am confident that we will prevail."

Kerry was also quick to condemn bin Laden's threats.

"As Americans, we are absolutely united in our determination to hunt down and destroy Osama bin Laden and the terrorists," he said during a campaign stop in Florida.

Al-Jazeera said it received the message earlier in the day, but would not say how.

White House spokesman Scott McClellan said U.S. intelligence officials believe the tape to be authentic.

The FBI is comparing the video to one broadcast Thursday night on the American network ABC. In that message, a masked man who says he is an American member of al-Qaeda says more attacks against the U.S. are imminent.

Bush's reaction on 9/11 ridiculed

This is the first time the world has heard from the fugitive al-Qaeda leader in more than a year – and the first time he has accepted responsibility for the 2001 attacks rather than just praising them.

He eluded capture when the United States invaded Afghanistan, where he was based, in late 2001. Many analysts believe he found refuge in a chain of mountains along the border with neighbouring Pakistan.

One of bin Laden's more explosive statements on the tape was that al-Qaeda's suicide airplane attacks on Sept. 11, 2001, would have been less severe if Bush had been more vigilant and acted more quickly.

Instead, he said, Bush continued listening to "a little girl's talk about her goat and its butting."

The president was visiting a school in Florida when an aide told him that a plane had flown into the World Trade Center. A cameraman captured the stunned politician continuing to listen to a young student reading My Pet Goat for the next seven minutes.

The al-Qaeda leader said the hijackers had planned to have all the attacks take place within 20 minutes because they were sure the Americans would react quickly and start shooting down errant airplanes.

Bush's delay "gave us three times the required time to carry out the operations, thanks be to God," bin Laden said.

A total of 58 minutes elapsed between the time the first plane hit the first Manhattan office tower and the moment the third plane crashed into the Pentagon – the Defence Department headquarters – in the Washington area.

A fourth plane crashed into a Pennsylvania field after passengers learned what had happened to the other hijacked airplanes and stormed the cockpit in order to divert it from a fourth populated target. That crash came one hour and 25 minutes after the initial airplane hit its target.

Invasion of Lebanon led to Sept. 11 attacks

The al-Qaeda leader said he decided that militants should start planning to attack the United States in the wake of Israel's 1982 invasion of Lebanon, when apartment towers in Beirut were bombed. The U.S. backed Israel in that action, he said.

Bin Laden also said Bush had misled the American people in the three years since al-Qaeda's 19 hijackers accomplished their deadly mission.

"Bush is still deceiving you and hiding the truth from you and therefore the reasons are still there to repeat what happened," he said.