Computer experts at the CIA tracked down the source of e-mails threatening to assassinate the President of the United States, only to find that they had come from two British schoolboys.

The 15-year old boys used a computer terminal in their classroom to send the emails to the White House website.

The teenagers used fake email addresses to avoid being found out, but it took just a few days for American secret agents to trace the origin of the messages to a Staffordshire secondary school.

Heather Bowman, headteacher of Blake High School in Cannock, Staffordshire, said that the prank proved all communication was now "traceable and attributable".

A police spokeswoman said staff at the school quickly discovered which boys had been using the terminal through "a process of elimination".

Special Branch officers then visited the teenagers at their home and gave them a reprimand. A police spokeswoman confirmed that officers had interviewed two Cannock schoolboys, but that no further action would be taken.

She added that the threatening emails were directed at Bill Clinton and not George W Bush and his family as had previously been reported.

It seems the boys had been paying attention in their computer classes, but they could be cruising for an F in Law.