Two UK men - a 19-year-old electrician and an unemployed 21-year-old - are being interviewed today by the National Hi-Tech Crime Unit (NHTCU).

The move follows the execution of search warrants this morning in County Durham. Two addresses were searched and evidence retrieved relating to computer and drugs offences.

The operation was jointly conducted with officers from Durham Constabulary and the US multi-agency CATCH team (Computer and Technology Crime Hi-Tech Response Team), which is based in Southern California.

A simultaneous search warrant was executed at an address in Illinois in the US, where additional evidence in the case was seized.

The two UK-based men have been identified as members of an international hacking group known as "THr34t-Krew".

The NHTCU claims this group is behind a piece of malware known as the TK worm, which has infected approximately 18,000 computers worldwide. The cost of the disruption caused is estimated by police to be £5.5m.

Detective Superintendent, Mick Deats, Deputy Head of the NHTCU, said in a statement: "Hacking and virus writing are serious crimes. They are costing UK firms millions of pounds in lost business and downtime. Our task is to track down those people who seek to hamper companies by reducing their ability to do business. "

The NHTCU was unable to comment further due to criminal proceedings now being active in respect of all the above named charges.