The United States generates more malicious computer activity than any other country, and sophisticated hackers worldwide are banding together in highly efficient crime rings, according to a new report.

Researchers at Symantec, the online security company, also found that fierce competition in the criminal underworld is driving down prices for stolen financial information.

Criminals may buy verified credit card numbers for as little as $1 (51p), and they can buy a complete identity – a date of birth, bank account number, credit card details and government-issued identification numbers – for $14 (£7.20), according to Symantec’s twice-yearly Internet Security Threat Report.

Researchers at the security software company found that about a third of all computer attacks worldwide in the second half of 2006 originated from machines in the United States.

That makes the US the most fertile breeding ground for threats such as spam, phishing and malicious code. The runners-up were China, which generates 10 per cent of attacks, and Germany, which generates 7 per cent.