NEW YORK - The American Civil Liberties Union sued senior US government officials on Tuesday to strike down the National Security Agency's broad telephone surveillance, a challenge that may have improved chances of succeeding as a result of recent leaks about the program.

The lawsuit filed in US District Court for the Southern District of New York claims the US government's collection of vast communications records violates rights to free speech and privacy as guaranteed by the US Constitution.

The suit was filed amid a furor over leaks by former NSA contractor Edward Snowden, who disclosed a massive government program to collect and store phone and Internet records from major telecommunications companies.

Legal experts said the leaks could help the ACLU to succeed where a previous suit involving Amnesty International failed.

After news stories from Snowden's leaks appeared in the Guardian of Britain and the Washington Post, US National Intelligence Director James Clapper declassified some details of the program, acknowledging it existed.

In Amnesty's challenge to the surveillance program, the US Supreme Court in February ruled 5-4 in favor of the government in part because it said the plaintiffs could not prove their phones had been tapped.

"Because the government has told us all that it is collecting the metadata, then that (Supreme Court reasoning) goes away," said Neil Richards, a professor at Washington University School of Law in St. Louis, Missouri.

John Mahoney, a partner at the Washington law firm Tully Rickney, agreed that Clapper's acknowledgement of the program last week had opened the door to a legal challenge.

"This suit has got legs because I do think this (surveillance) program might be overbroad constitutionally," Mahoney said. "I'm all for national security and I do national security law for a living, but to just broadly capture every phone call and every Internet message by every citizen of the United State seems a bit much."

The US Justice Department declined to immediately comment on the suit, saying it needed time to review it and respond.