European firms have nothing to fear from the Leave virus that prompted warnings from a US government agency, according to antivirus vendors.

The virus mimics a denial of service attack, placing a code inside a computer to synchronise it with the US Naval Observatory's clock. However, it only infects computers which have had the Sub-Seven Trojan installed.

Network Associates said it "has not received any samples of this threat from the field. However, reports from very credible sources were a contributing factor when assessing this threat as a Medium Risk."