FBI Director Christopher Wray urged Congress on Tuesday to renew a law authorizing US agencies to spy on non-Americans around the world, arguing that allowing it to lapse would be equivalent to "unilateral disarmament."

Section 702 of the Foreign Intelligence Surveillance Act (FISA), as it is known, is scheduled to expire at the end of December.

Wray, testifying before the Senate Judiciary Committee, said Section 702 is a vital tool used by law enforcement to fight terrorism, cybercrime and drug trafficking.

"Stripping the FBI of its 702 authorities would be a form of unilateral disarmament," the FBI director said, calling it "indispensable to our efforts to combat threats posed by foreign adversaries."

"702 allows us to stay a step ahead of foreign actors located outside the United States who pose a threat to national security," he said.

Wray added: "702 is key to our ability to detect a foreign terrorist organization overseas directing an operative here to carry out an attack in our own backyard."

Section 702 allows the Federal Bureau of Investigation, the Central Intelligence Agency and the National Security Agency to conduct electronic surveillance — including looking at emails and text messages — on non-Americans abroad without the need for a court warrant.

However, Section 702 faces resistance from civil liberties and privacy groups and some lawmakers — both Democrat and Republican — due to controversies over searches entangling US citizens.

The current center of opposition is led by Republicans taking their cue from Donald Trump, the indicted former president whose 2024 election comeback bid is partly based on portraying the FBI as politically biased against him and his supporters.

Earlier this year, an independent advisory panel to President Joe Biden acknowledged there had been violations in the use of 702 but said the tool is too vital to abandon.

Section 702 was first established in 2008 and has been renewed twice.

Senator Dick Durbin, the Democratic chair of the Senate committee, welcomed recent reforms of 702 rules but said he remained concerned about "protecting the communications of innocent Americans from warrantless surveillance."

"I look forward to continuing to work with you to reauthorize 702 with the significant reforms we need to protect the privacy of innocent Americans," Durbin told the FBI director.