Outgoing US President Bill Clinton has announced plans to ease export controls on high-performance computers made in the US, saying there are no "meaningful or effective" ways to control such technology.

This is the sixth time since 1993 that the Clinton administration has moved to loosen controls on computer exports, which were originally introduced to prevent advanced technology falling into the hands of potential adversaries. The computer industry has argued for several years that restrictions on the export of computers have not kept up with the advancement of technology.

While the White House would "prefer to remove most controls on computer hardware exports", it said in a statement that it is prohibited from doing so by a 1997 law. The White House also said the incoming administration "needs an opportunity to examine such a proposal".

White House Chief of Staff John Podesta told reporters that because of the wide availability of high-performance computers, the US's ability to limit their acquisition by potentially unfriendly countries is "already largely ineffective and it will be increasingly so in a very short time frame".

Podesta also said the US would beef up export restrictions on critical nuclear and military software applications that pose a threat to national security if they fall into the wrong hands.

The current export control system categorises foreign countries on a tier basis. While there are few restrictions on exports to tier one countries, which includes Western Europe and other close US allies, the US will maintain an embargo on export to tier four or "terrorist countries", which include Iran, Iraq, Libya, North Korea, Cuba, Sudan and Syria.

The administration also announced it was eliminating the tier two category, shifting countries in this group which include many South and Central American nations and some Asian countries, into tier one. Sales to tier three countries such as India, Pakistan, Russia, China, Vietnam and nations in the Middle East will not need special export licenses if the computers perform below 85,000 million theoretical operations per second.

Bill Reinsch, under-secretary for export administration at the US Commerce Department, said the decision to ease export controls would enhance national security "by maintaining the health of our computer industry".

Reinsch also said easing restrictions on foreign shipments would be a boon to the computer industry, which has long complained that strict controls have damaged overseas business.

The Computer Coalition for Responsible Exports (CCRE), which includes IBM, Hewlett Packard and Dell, issued a statement approving the move.

"We applaud the Clinton Administration's ability to keep government regulations in line with the rapid pace of technological change in our dynamic industry," said IBM chairman and chief executive and joint-chairman of CCRE, Lou Gerstner.