Gabbitas, the publisher of the UK Independent Schools Guide, has reiterated its claim that the data breach in which personal data on 1,367 school children was leaked online was due to "unauthorised access", not "administrational error".

The company issued a statement "following further misleading speculation in the media" to insist that the data breach was due to "unauthorised access to .. the site, rather than an administrative error, as reported recently".

Critics had questioned how and why an external party would cause the data, which included details of their personality, learning difficulties and health, and even comments about them from their parents, to made be available through a Google search.

“Gabbitas is deeply concerned that one of its websites appears to have been accessed illegally and has notified the matter to the Police and the Information Commissioner’s Office," the firm said in a statement. "Gabbitas is cooperating fully with both organisations in their respective investigations."

While the firm says it is taking measures to ensure the security of its other sites, it ‘strongly believes’ all of its client data is secure, adding that unless it was required to do so, it would not be releasing any further details during the ongoing investigation.

The breach was originally exposed in an investigation by the Daily Telegraph.