The law, approved by the Senate and the House just before Congress adjourned for its summer break, was deemed a priority by Bush and his chief intelligence officials.

Bush signed the bill into law on Sunday afternoon at his retreat at Camp David, Md.

"When our intelligence professionals have the legal tools to gather information about the intentions of our enemies, America is safer," Bush said. "And when these same legal tools also protect the civil liberties of Americans, then we can have the confidence to know that we can preserve our freedoms while making America safer."

The administration said the measure is needed to speed the National Security Agency's ability to intercept phone calls, e-mails and other communications involving foreign nationals "reasonably believed to be outside the United States."

The law is designed to capture communications that pass through the United States.

Civil liberties groups and many Democrats say it goes too far, possibly enabling the government to wiretap U.S. residents communicating with overseas parties without adequate oversight from courts or Congress.

The new law updates the Foreign Intelligence Surveillance Act, and it will expire in six months unless Congress renews it. Bush wants deeper, permanent changes.

"We must remember that our work is not done," Bush prodded. "This bill is a temporary, narrowly focused statute to deal with the most immediate shortcomings in the law."