The US Senate has passed legislation that would allow families of 9/11 victims to sue Saudi Arabia's government for damages.
The development sets up a potential showdown with the White House which has threatened a veto.
The Justice Against Sponsors of Terrorism Act (JASTA) legislation was passed unanimously on Tuesday.
It must next be taken up by the US House of Representatives where no vote has yet been scheduled.
Saudi Arabia denies involvement in the September 11, 2001 attacks on the World Trade Center and the Pentagon 15 years ago, threatening to sell the kingdom's $750bn worth of assets in the US if such legislation becomes law.
President Barack Obama has opposed the legislation.
Adel al-Jubeir, the Saudi foreign minister, has said his country's objection to the bill is based on principles of international relations.
"What [Congress is] doing is stripping the principle of sovereign immunities which would turn the world for international law into the law of the jungle," he said in a statement on Tuesday.
Josh Earnest, White House spokesperson, said Obama continues to "strongly oppose" the Senate measure as eroding the principle of sovereign immunity and increasing the vulnerability of US interests in foreign courts.
"Given the concerns, it's difficult to imagine the president signing this legislation," Earnest said.
If passed, the legislation would narrow the sovereign immunity of other governments in federal courts, allowing lawsuits against foreign states for injuries, death and damages inside the US as a result of a tort, including an act of terrorism, committed anywhere by a foreign state or official.
"Victims and families who have lost loved ones in terror attacks deserve the opportunity to seek justice," John Cornyn, Texas senator and sponsor of the legislation, said.
'One step closer'
Charles Schumer, New York senator, said the US was "one step closer to justice for the victims of the 9/11 terrorist attacks" and urged the House to vote on the measure.
"In their pursuit of justice, 9/11 families were told American law prevented them from pursuing justice against those who funded the attacks," he said.
"JASTA will help these families seek justice and also serve as a deterrent to other nations who'd assist in terror attacks against Americans."
Fifteen of the 19 hijackers who carried out the attacks were Saudi citizens.
In a 2003 report, the US government's 9/11 Commission said there was no evidence Saudi Arabia had funded al-Qaeda.
Last year, a US judge dismissed claims against Saudi Arabia by families of victims who accused the country of providing material support to al-Qaeda.
US District Judge George Daniels in Manhattan, New York, said Saudi Arabia had sovereign immunity from damage claims by families of nearly 3,000 people killed in the attacks, and from insurers that covered losses suffered by building owners and businesses.