A bill that would allow the families of 9/11 victims to sue the Saudi government has passed a key hurdle in the US Senate.

The Justice Against Sponsors of Terrorism Act (JASTA) now moves to the House of Representatives.

Saudi Arabia's foreign minister warned that the move could cause his government to withdraw US investments.

President Barack Obama said he will veto the bill, but a Democratic senator is "confident" he'd be overruled.

If it became law the legislation would allow victims' families to sue any member of the government of Saudi Arabia thought to have played a role in any element of the attack.

Saudi Arabia denies any involvement in the 2001 attack on the World Trade Center and the Pentagon, which killed nearly 3,000 people.

Fifteen out of the nineteen hijackers in 2001 were Saudi citizens.

In 2004 the 9/11 Commission Report found "no evidence that the Saudi government as an institution or senior Saudi officials individually funded the organisation".

A White House spokesman said President Obama had serious concerns about the bill, and it was difficult to imagine he would sign it into law.

It was sponsored by Democrat Senator Chuck Schumer of New York and Republican Senator John Cornyn of Texas and is expected to be passed by the House of Representatives as well.
Senator Schumer said: "Today the Senate has spoken loudly and unanimously that the families of the victims of terror attacks should be able to hold the perpetrators even if it's a country a nation accountable.

"It will serve as a deterrent and warning to any other nation who assists in terror attacks against American."

He said he was confident the bill would be passed by a large margin in the Republican-controlled House of Representatives.

On Tuesday, Saudi Arabia denied it had threatened to sell its US bonds, which would pull billions of dollars from the US economy.

"We said that a law like this is going to cause investor confidence to shrink," Foreign Minister Ahmed Al-Jubeir said while attending a conference in Geneva. "Not just for Saudi Arabia, but for everybody".

Last year an inmate in US custody, Zacarias Moussaoui, claimed that a Saudi prince had helped finance the attack that flew passenger planes into the World Trade Center in New York and the Pentagon in Virginia.

A fourth plane crashed into an empty field in western Pennsylvania.

Saudi Arabia had rejected the accusation from a "deranged criminal" with no credibility.