By Jeremy Cooke
BBC News, New York
A US federal court has dismissed proceedings under which the Saudi government was accused of providing logistical support to al-Qaeda.
About 3,000 people died in the 11 September attacks
New York District Court Judge Richard Casey ruled that the Saudi government, its defence minister and ambassador in London have immunity from litigation.
Following the 9/11 attacks, relatives of victims, private firms and insurers sued for multi-billion damages.
Many of them named Saudi Arabia as a defendant in civil lawsuits.
'Blow for plaintiffs'
Ruling in a number of such cases, Judge Casey said the Saudi government and its officials have immunity to claims that they provided financial and logistical support to Osama bin Laden's network.
The judge also dismissed claims against the Al Rajhi Banking and Investment Corporation, the Saudi American Bank and the Arab Bank Plc.
Although the case against other Arabic banks, charities and companies, including the Saudi Bin Laden Group go forward, the ruling is a blow for the plaintiffs.
Justin Green, a lawyer representing more than 500 victims of the 11 September attacks, said the ruling would probably lead to the dismissal of other similar cases, but that an appeal was being considered.
The district court's ruling will come as little surprise to legal analysts here.
Many of the cases are regarded as protective actions by companies and individuals mindful that they may have to demonstrate in any future litigation that they have done everything possible to seek justice for the victims of the terror attacks.