Updated

A civil liberties group sued the U.S. government Monday, saying various agencies have failed to provide adequate documents related to what it calls the sweeping monitoring of Americans' international communications.

The American Civil Liberties Union said in the lawsuit in federal court in Manhattan that its Freedom of Information Act requests since May had been largely ignored by the National Security Agency, the Central Intelligence Agency, the Department of Defense, the Department of Justice and the Department of State. It sought a court order to force the government to turn over information about the rules governing how it monitors the international calls and the emails of Americans.

The ACLU said it wants to learn what protections are given to Americans whose communications are monitored and whether they are legally sufficient. The lawsuit said legal standards and limitations are sought rather than operational details.

A government spokeswoman said there was no immediate comment.

In a blog, ACLU staff attorney Alex Abdo said revelations over the last year have increased the public's understanding about how the government conducts surveillance when it sweeps up Americans' international communication when it takes place on U.S. soil. But he said there was little known about an executive order which allows U.S. agencies to monitor Americans' communication in other countries.

According to the lawsuit, the executive order signed in December 1981 and modified numerous times since allows surveillance that is not overseen by the Foreign Intelligence Surveillance Court. It said that while it was known that the order permits the government to target foreigners abroad for surveillance, recent revelations have confirmed that the government interprets the authority to permit sweeping monitoring of Americans' international communications.

"How the government conducts this surveillance, and whether it appropriately accommodates the constitutional rights of American citizens and residents whose communications are intercepted in the course of that surveillance, are matters of great public significance and concern," the lawsuit said.

Abdo said the lawsuit brought by the ACLU and the Media Freedom and Information Access Clinic at Yale Law School was filed after it was learned that the surveillance overseas is being conducted on Americans without any real oversight.

"We now know too well that unchecked surveillance authority can lead to dangerous overreach," he said.

The lawsuit cited news reports that NSA is collecting nearly 5 billion records per day on the locations of cell phones and hundreds of millions of contact lists or address books from personal email and instant messaging accounts.