Margaret Brown, Professor of Mathematics Education at King's College, London, and a member of the government's numeracy task force, is angry at the way the government presented the task force's final report earlier this month.

In practice little use is made of calculators by under-eights

"The task force slaved away to reach a compromise then this is totally ignored in the press release which announces that there is a ban on calculators," she told BBC News online.

This sort of "spin" was "disgraceful", she said. "I don't see how a reasonable democracy can work like this."

The press release from the Department for Education said: "The national numeracy strategy will see pupils in every primary school benefiting from the new emphasis on the basics." It listed 11 action points, of which the fifth was: "a ban on the use of calculators by children up to the age of eight and restricted use throughout the remainder of primary school".

This dominated the newspaper headlines the following day - and an 'exclusive' report in the News of the World the previous Sunday had included the sub-heading "Blair also orders ban on calculators".

'Regrettable'

Professor Brown's decision to speak out on the issue is prompted by concern that teachers will be influenced by the way it has been reported.

Another member of the task force who did not wish to be identified complained of "macho posturing" by ministers.

"We certainly agree that using calculators for small sums instead of doing mental arithmetic is not a good idea," Professor Brown said. "They are not used anyway much in key stage one [ages five to seven] except to teach concepts and so on, and they tend to be used well for that and we encourage teachers to keep on using them for that," she said.

The chair of the numeracy task force, Professor David Reynolds of Newcastle University, was careful in his choice of words. "It's the confusion that's the problem," he said.

"It is regrettable that there is such confusion and mixed messages on calculators which is distracting attention from the clarity of views on other issues. I think it's important that any confusion is removed next term."

Professor Brown believes that the Education Secretary, David Blunkett, is pursuing a private obsession.

"I hope that we will at least persuade teachers that on the whole they are doing a good job and they don't have to stop."

The secretary of state cannot in any case enforce a ban except by passing new legislation, she argues - but it would be a brave school that ignored formal guidance from the Department for Education.