"In the war on terror, we cannot afford to be without this law for a single moment," the president said in a live broadcast on Saturday from the White House of his weekly radio address.

His comments came a day after Senate Democrats, with the aid of a handful of Republicans, succeeded in stalling the bill already approved by the House.

The vote to advance the measure, 52-47, fell eight votes shy of the 60 votes required to end debate.

"That decision is irresponsible and it endangers the lives of our citizens. The senators who are filibustering must stop their delaying tactics and the Senate must reauthorise the Patriot Act," Bush said.

"The senators who are filibustering must stop their delaying tactics and the Senate must reauthorise the Patriot Act"

US President George Bush

Opponents of renewing the law, most of whom are Democrats, argue that it threatens constitutional liberties at home.

Most Republicans and other supporters say the act is essential for protecting the country against terrorists.

The law was enacted in the aftermath of the attacks of September 11, 2001.

Of the 55 Republicans in the Senate, four helped to block its passage while two of the 45 Democrats pushed to pass it.

Some of the most contentious elements of the Patriot Act include powers granted to law enforcement agencies to gain access in secret to library and medical records and other
personal data during investigations of suspected terrorist activity.

'Lone wolf'

The law allows the government to conduct roving wiretaps involving multiple phones and to wiretap "lone wolf" terrorists who may operate on their own, without control from a foreign agent or power.

If the law is not renewed, its powers would expire on December 31 only for new nvestigations of people whose criminal activity began after December 31 and who were not associated with anyone who was under investigation before December 31.

"The terrorist threat to our country will not expire in two weeks"

President Bush

The debate over the Patriot Act was fueled anew by a New York Times report that Bush had secretly authorised eavesdropping on individuals in the United States without first gaining permission from the courts.

In his radio address, Bush defended his decision to authorise the National Security Agency to conduct the secret probes much as he defended the Patriot Act, saying both had saved lives and prevented more attacks.

Noting that key provisions of the Patriot Act are set to expire in two weeks, the president said: "The terrorist threat to our country will not expire in two weeks. The terrorists want to attack America again, and inflict even greater damage than they did on September the 11th."

"Congress has a responsibility to ensure that law enforcement and intelligence officials have the tools they need to protect the American people."