London: World’s first bullying alert system for social networking site Facebook has been developed which will scan texts and flag up abusive behaviour.

British man Paddy Clarke, who has developed the software, claims it to be the world’s first alert system.

Clarke's software scans walls and inboxes for trigger words and phrases such as ‘gay’ and ‘fat’ and alerts parents when they appear.

He came up with the idea after reading a string of cyber-bullying horror stories, a daily reported.

He hoped his system, called ‘Know Diss’, will keep children safe from online bullies. "Cyber-bullying is very topical at the moment, but this software is the only one in the world to search through text on social networking sites to protect children,” he said.

"Know Diss is a very simple concept. It is also a partnership between parent and child because one cannot sign up without the other," Clarke said.

Clarke, a consultant in pain relief at Gloucestershire Royal Hospital in Gloucester, along with friend Alan Saul designed and implemented Know Diss, which costs 12 pounds for a yearly subscription.

Together they trawled through sites such as Urban Dictionary and watched the television series Skins to build their comprehensive database of insults. Clarke's program continuously searches through all text on Facebook accounts signed up to the service, including messages, picture comments and posts. It uses a database of several thousands of words to identify bullying trigger words in a number of spelling variations.

Parents and their children must both sign up by email for the software to work. A link is sent for them to click in order to download Know Diss.

When a bullying phrase is detected, it is copied and immediately emailed to the child's parent or "Facebook guardian" who can decide whether further action is needed.