A problem with the IT system used by a new contractor has delayed the publication of Key Stage 2 and Key Stage 3 test results, the National Assessment Agency (NAA) has announced.

Results for both levels were scheduled for publication on 8 July, but KS2 results will be delayed until 15 July, while KS3 results will not be released until the end of that week.

Pupils will still receive hard copies of their results in the post, according to a statement by the NAA. "This year's arrangements for marking the national curriculum tests have varied from previous years," it said.

"There is a new marking contractor, ETS Europe, and a series of additional checks to give greater assurance of high quality marking," it said.

"The main causes of this delay are the belated completion of the marking process and a series of technical issues. This is a serious failure by ETS Europe, for which we apologise to schools, pupils and parents."