The Association of School and college leaders (ASCL) has fought back against claims that the online encyclopaedia Wikipedia is not suitable for use in schools.

The backlash came after education secretary Alan Johnson was criticised by Wikipedia’s former owner, Larry Sanger, for praising the site and encouraging pupils to use it at yesterday’s annual conference for the National Association of Schoolteachers and Union of Women Teachers.

Sanger, who is no longer involved with the site, said that the community that produced Wikipedia was "often dysfunctional" and the content was unreliable. He also claimed that the site was "broken beyond repair" due the fact that anyone could edit or add to entries, leading to misinformation.

However Martin Ward deputy general secretary at the Association of School and College Leaders (ASCL) disagreed: “While our members are free to use whatever policies they deem suitable to teach, we would recommend the use of Wikipedia. It is a valuable resource and we encourage children to use it.”

He also outlined other benefits the site could be used for in schools. “The important thing to remember when it comes to the internet is that is inherently full of misinformation so children can learn here how to be critical and sceptical of what they read just like they would be with any other medium, be it newspapers or even school text books.”

This view was shared by Wikipedia representative David Gerard: “Teachers should approach the site as a means for teaching children how to read critically,” he said.

“Because of the nature of the site some of the content cannot be reliable but this teaches children not to take things they read at face value and approach any piece of literature with a sceptical mind.”

Wikipedia, which launched in 2001, is written by volunteers. In January, the site had roughly 7m entries, in 251 languages.

Mr Johnson had earlier told the teacher's union: "Wikipedia enables anybody to access information which was once the preserve only of those who could afford the subscription to Encyclopaedia Britannica and could spend the time necessary to navigate its maze of indexes and content pages."