Zacarias Moussaoui, an inmate at a Colorado prison, is shown in this undated police photograph. [Photo/Agencies]

NEW YORK - Lawyers for victims of the Sept 11 attacks say they have new evidence that agents of Saudi Arabia "directly and knowingly" helped the hijackers, including sworn testimony from the so-called 20th hijacker and from three principals of the US government's two primary probes of the attacks.

The Embassy of Saudi Arabia in Washington said in a statement Wednesday that Zacarias Moussaoui's claims come from a "deranged criminal" and that there is no evidence to support them. It said Saudi Arabia had nothing to do with the deadly 2001 attacks.

The lawyers filed documents in Manhattan federal court to buttress claims Saudi Arabia supported al-Qaida and its leader at the time, Osama bin Laden, prior to the attacks. They have always said "the Saudi government directly and knowingly assisted the 9/11 hijackers," but now say facts and evidence supporting the assertion "are compelling."

They said an "expansive volume" of new evidence - including US and foreign intelligence reports, government reports and testimony from al-Qaida members - support lawsuits seeking billions of dollars from countries, companies and organizations that aided al-Qaida and other terrorist groups.

They said evidence likely to be released soon includes a congressional report detailing evidence of Saudi 9/11 involvement and nearly 80,000 pages of material relating to an FBI probe of Saudis who supported 9/11 hijackers in Florida.

They also cited their own research, including last year's Moussaoui interview at the maximum-security prison in Florence, Colorado.