The United States said last night it still had no idea who or what was behind a wave of Internet vandalism and ordered a review of its defence computer networks to ensure they had not been tampered with.

The Defence Department said 10,000 or so computer networks would be looked at to make sure none had been affected by the cyber-vandalism that crippled major websites this week.

The Clinton administration is using this week's website woes to push for bigger budgets to short-circuit computer hack attacks by anyone from a foreign foe to as 15-year-old boy.

In a fiscal 2001 spending plan sent to Congress on Monday, President Clinton sought $37 million (€37.5 million) more than this year for the Justice Department to fight Internet crime, a rise of 15 per cent.