WASHINGTON (Reuters) - U.S. State Department officials told members of Congress on Tuesday that legislation that would allow families of Sept. 11 victims to sue Saudi Arabia is opposed by important U.S. allies and posed a national security risk.

But many members of a House of Representatives Judiciary Committee subcommittee expressed strong support at a hearing for the “Justice Against Sponsors of Terrorism Act,” or JASTA, which the Senate passed in May by unanimous voice vote despite President Barack Obama’s veto threat.

The Saudis, who deny responsibility for the 2001 attacks, strongly oppose the legislation. Other governments have also raised objections. The Dutch parliament warned that JASTA would represent a breach of Dutch sovereignty. A member of the British parliament wrote a column opposing it.

Anne Patterson, the State Department’s assistant secretary for Near Eastern affairs, and Brian Egan, its legal counsel, testified that the measure could lead to lawsuits against the United States and discourage security cooperation such as intelligence sharing between governments.

“We cannot win the fight against ISIL without full international cooperation,” Patterson said, using an acronym for the Islamic State militant group.

But the bill’s supporters say it would provide justice to those who lost loved ones in the attacks 15 years ago. They argue that if Saudi Arabia was not responsible for the attacks, it would win any lawsuits.

Representative Jerrold Nadler, a Democrat who represents New York City, said worry about retaliation should not keep the measure from becoming law. “That is no reason to deny justice to the victims of 9/11 and their families,” he said.

If it became law, JASTA would remove sovereign immunity preventing lawsuits against governments for countries found to be involved in terrorist attacks on U.S. soil. It would allow survivors of the attacks, and relatives of those killed in the attacks, to seek damages from other countries.

In this case, it would allow lawsuits to proceed in federal court in New York as lawyers try to prove that the Saudis were involved in the attacks on the World Trade Center and Pentagon.

There was no immediate word on when the House might vote on JASTA. The House was due to adjourn later on Thursday for its summer recess and will not return to Washington until September.