"We regret that, on Monday evening, the wrong paper was temporarily uploaded on to our secure website, which has no public access and is only available to our test markers.

"We apologise to schools, teachers, parents and pupils for this error at this sensitive time. We are conducting an investigation to make sure it cannot happen again. As part of this investigation, we will seek to find out which individual passed this information into the public domain, in breach of their commitments to us and their fellow markers.

"As soon as we were made aware, the website in question was taken down. The appropriate papers are now available on the site to facilitate the marking process.

"A small number of markers accessed the paper, although as contracted markers they are bound by confidentiality and have a duty not to share any papers.

"We do not have any evidence that the content of the paper has been compromised and it is important that the test should go ahead, not least as it follows so much hard work by teachers and pupils."