The bulk collection of Americans' phone records by the government exceeds what Congress has allowed, a federal appeals court said Thursday as it asked Congress to step in and decide how best to balance national security and privacy interests.

A three-judge panel of the 2nd U.S. Circuit Court of Appeals in Manhattan permitted the National Security Agency program to continue temporarily as it exists, but all but pleaded for Congress to better define where the boundaries exist.

"In light of the asserted national security interests at stake, we deem it prudent to pause to allow an opportunity for debate in Congress that may (or may not) profoundly alter the legal landscape," said the opinion written by Circuit Judge Gerald Lynch.

"If Congress decides to authorize the collection of the data desired by the government under conditions identical to those now in place, the program will continue in the future under that authorization," the ruling said. "If Congress decides to institute a substantially modified program, the constitutional issues will certainly differ considerably from those currently raised."

The appeals judges said the issues raised in a lawsuit by the American Civil Liberties Union illustrated the complexity of balancing privacy interests with the nation's security.

A lower court judge in December had thrown out the case, saying the program was a necessary extension to security measures taken after the Sept. 11, 2001, terror attacks. The appeals court, which heard two hours of arguments, said the lower court had erred in ruling that the phone records collection program was authorized in the manner it was being carried out.