NEW YORK -- Lawyers for families of Sept. 11 terrorist-attacks victims appealed to a federal appeals court Thursday to restore Saudi Arabia as a defendant in a lawsuit.

The appeal, filed with the 2nd U.S. Circuit Court of Appeals, asked the court to reverse a lower-court judge's ruling in August that dismissed the nation as a defendant.

Attorney Jerry Goldman said the appeal was filed on behalf of nearly 3,000 families who lost loved ones on Sept. 11, 2001, as well as others who were injured. Fifteen of the 19 hijackers in the 2001 attacks were citizens of Saudi Arabia.

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He said a Manhattan judge was wrong to conclude that claims in the lawsuit lacked sufficient support and that Saudi Arabia was protected by sovereign immunity.

"In light of the quality and quantity of material submitted, we believe that the plaintiffs have demonstrated that the Kingdom of Saudi Arabia committed acts on U.S. soil that were instrumental in the planning and execution of the 9/11 attacks," Goldman said in a statement.

Lawyers for Saudi Arabia did not immediately return a message seeking comment.

Saudi Arabia had been reinstated by the 2nd Circuit in December 2013 after a lower-court judge had previously dismissed the nation as a defendant on sovereign immunity grounds.

Saudi Arabia was among the countries, companies and organizations sued in 2002 and afterward by families who claimed they aided al Qaeda, Osama bin Laden and other terrorist groups. The lawsuits sought billions of dollars in damages.

In the lawsuits, lawyers argued that the Sept. 11 attacks, which destroyed the World Trade Center and killed thousands of people, had been planned for years by a network of Islamic militants with the assistance of banks, governments and individuals.