One of the largest ever lawsuits relating to the September 11 terror attacks has been filed against Saudi Arabia in New York.

Families of 850 victims who died and the 1,500 injured, are suing the Middle Eastern country's government, accusing it of providing material and financial assistance to al Qaeda in the years leading up to worst ever terrorist attack on US soil.

Of the 19 hijackers who took over the aeroplanes during the attack, 15 were from Saudi Arabia.

The complaint accuses Saudi officials of being aware that money was redirected to al Qaeda from charities in the country, so they could finance their attacks.

The plaintiffs have been able to utilise the US's Justice Against Sponsors of Terrorism Act. Passed last year, it allows lawsuits to be brought against foreign states.

Barack Obama opposed the law but was overruled by Congress and since then there have been six other lawsuits filed against Saudi Arabia by the families of 9/11 victims.

Explaining the lawsuit’s reasoning, co-chairman of the plaintiffs' committee Jim Kreindler told CNN: “9/11 could not have happened without Saudi Arabia's support for al Qaeda."

His colleague Jerry Goldman added: “We intend, just like we have for over the last 13 years, to move forward to seek justice on behalf of all the families, and accountability on behalf of all the people in this country."

The voices of 9/11: The ripples still being felt around the world Show all 4 1 /4 The voices of 9/11: The ripples still being felt around the world The voices of 9/11: The ripples still being felt around the world The voices of 9/11: The ripples still being felt around the world The voices of 9/11: The ripples still being felt around the world What remains: A New York City firefighter looks up at what remains of the World Trade Centre on 13 September, 2001 REUTERS The voices of 9/11: The ripples still being felt around the world Five days on: FEMA workers survey the wreckage of the World Trade Centre on September 16, 2001 REUTERS

Their complaint cites both CIA and FBI reports, including the "28 pages" a section of the 2002 Joint Inquiry into Intelligence Community Activities before and after the Terrorist Attacks of September 11, 2001, that was declassified last year.

That suggested that the hijackers received assistance and financial support from individuals connected to the Saudi Arabian government, implicating intelligence officers, embassy staff, and members of the country's royal family.

The Saudi government has denied any involvement in the attacks and has refused to comment on the latest case to the media.