The cost of piloting controversial new reading tests for all pupils at the end of Year 1 is being kept secret by the Government.
The tests, due to be introduced in summer 2012, will be piloted in about 300 schools in June this year. They will consist of a child reading about 40 words - some of which will be "non-words" - to give an idea of whether pupils have grasped the basic skills.
The ten-minute tests, administered by teachers, have come under fire from unions and phonics experts for being a waste of money.
In response to a Freedom of Information request by The TES, the Department for Education said it would not be in the public interest to disclose the amount of money set aside for the pilots.
It said it was important to balance the disclosure of information with the need to allow ministers to take advice and formulate policy in private and that the costs would not be made public until later this year.
National Association of Head Teachers general secretary Russell Hobby said: "Apparently, it's in the public interest to disclose the salaries of heads and when they're off sick, but it is not in the public interest to disclose the cost of a test that people are very dubious about.
"Obviously, the idea is to raise standards, but if it is a hugely expensive way of doing that there may be better things to spend the money on."
There have also been concerns from academics about the tests, saying that including non-words could confuse some children who can read, as well as not picking up children who can pronounce words fluently without really understanding them.