Washington  - The US Senate on Wednesday passed a long- awaited bill that places fresh restrictions on a government eavesdropping programme which had been significantly expanded after the September 11, 2001, terrorist attacks.

The legislation, thrashed out between Republicans, Democrats and the White House after a year of wrangling, allows the intelligence community to acquire broad warrants to listen in on calls between Americans and suspected terrorists outside of the country.

President George W Bush has argued that the surveillance programme is crucial to preventing future terrorist attacks against the United States.

A bitter debate has simmered for years over the proper balance between national security and civil liberties. Even on Wednesday, opponents objected because the compromise bill still allows warrantless surveillance of Americans if the information is collected overseas.

The Senate adopted the compromise bill 69-28 after the House of Representatives approved similar legislation last month. The bill is expected to be signed by the US president.

The revised Foreign Intelligence Surveillance Act broadens congressional oversight of the programme and effectively reestablishes the primacy of a special court designed to approve all government requests to listen in on telephone calls or emails collected in the United States.

The non-public FISA court, set up in 1978 to allow the government to produce classified information, had been largely bypassed by the Bush administration since the September 11 attacks on New York and Washington.

The Senate bill controversially grants immunity from lawsuits to telecommunications companies that provided information without warrants to the Bush administration in the years after September 11.

Bush's warrantless surveillance programme was first revealed by media organizations in 2005, and about 40 lawsuits against telecoms firms are now pending in US courts. Many Democrats in the Senate strongly opposed blocking those cases from proceeding.

"Now is not the time to close the courthouse doors on this issue," Democratic Senator Christopher Dodd, a leading opponent of the bill, said in debate. "My trust remains in the courts."

Republicans argued that telecoms firms should not be subjected to civil suits for helping to protect national security. The bill would still allow the surveillance programme itself - and government officials who crafted it - to be brought before the courts.

The issue has become a hot topic on the election campaign trail. Democratic candidate Barack Obama faced a backlash from supporters last month for saying he approved of the compromise bill - an about- face from an earlier promise that he would oppose any legislation that provided immunity to telecommunications companies.

Republican rival John McCain has strongly supported the surveillance programme and immunity for telecoms. (dpa)