US President George W. Bush Thursday signed a controversial law expanding legal authority for wiretaps by spy agencies after a fierce battle in Congress.
As he signed the measure, Bush hailed the legislation as "vital to the security of our people."
"The bill will allow our intelligence professionals to quickly and effectively monitor the communications of terrorists abroad while respecting the liberties of Americans here at home," he said.
The law includes retroactive immunity for telecommunications firms which aided warrantless government surveillance operations following the September 11 attacks in 2001, which was a key demand of the White House.
The bill had sparked fierce debate between civil liberties advocates who argue it eroded checks on the power of government and intelligence officials who feared the row was compromising their power to thwart terror attacks.
Senators finally voted Wednesday 69 to 28 to pass the measure, after blocking several attempts to water down the immunity for telecom firms.
"Almost seven years have past since that September morning when nearly 3,000 men, women, and children were murdered in our midst," Bush said.
"The attack changed our country forever. We realized America was a nation at war. Against a ruthless and persistent enemy."
The president added: "The most important lessons learned after 9/11 was that America's intelligence professionals lack some of the tools they needed to monitor the communications of terrorists abroad.
"It's essential that our intelligence committee know who our enemies are talking to, what they're saying, and what they're planning."
