The BBC has confirmed that subscribers to its email newsletter about The Archers, the world's longest running radio serial, were accidentally sent the Sobig worm.

The Archers, an everyday story of country folk, is broadcast on BBC Radio 4. Listening figures have surged recently with interest in Brian and Siobhan's affair. Many listeners have subscribed to the email newsletter in order to receive daily updates on the soap opera's latest developments.

If the recipient of the Sobig worm double clicks on the email's attachment, the worm searches their Windows local hard drive, tries to extract a list of email addresses and attempts to forward itself to all these contacts. In this case, its replication was boosted by being spread via The Archers mailing list.

"The Sobig worm first appeared in mid January. It has had quite a big impact since then, indeed it was the fourth most prevalent virus during January 2003," said Graham Cluley, senior technology consultant, Sophos Anti-Virus. "Most anti-virus vendors released protection against the Sobig worm as soon as it was detected, so Archers fans who have recently updated their anti-virus software would have avoided infection."

Ironically, a current storyline has Jolene showing Joe Grundy how to send emails in the new cybercafe set up in The Bull, Ambridge's local pub.