The Government last night fired a broadside at teachers opposed to national English, maths and science tests.

Unions were warned they were "living in cloud cuckoo land" if they thought ministers would give in to demands for their abolition.

The National Union of Teachers' annual conference in Harrogate, North Yorkshire, is expected to reaffirm its opposition to the tests (Sats) tomorrow.

A poll yesterday showed most parents in England and Wales oppose testing seven-year-olds but want to keep them for 11 and 14-year-olds.

The survey by The Times Educational Supplement showed that, in England, 67 per cent were in favour of testing at 11, rising to 72 per cent in the case of 14-year-olds.

The Government is experimenting with less formal testing of seven-year-olds, and Schools Minister Stephen Twigg has said he expects the trial to be successful and to be extended to cover all primaries next year.

But the Government has rejected all calls to abolish National Curriculum tests for 11 and 14-year-olds in England.

The NUT last year balloted members on a boycott of this year's English, maths and science tests due to be taken by millions of children next month.

But it will not go ahead because too few eligible NUT members voted, although most of those who did supported a boycott.

Far left NUT members will tomorrow attempt to commit their ruling executive to urging other teacher unions to ballot their members on a boycott.

Earlier this week, in the first of the Easter teacher conferences, the more moderate Association of Teachers and Lecturers urged the Government to stop formally testing seven-year-olds, saying that it was harming children's education.

Partial support for the unions' stance came from the National Confederation of Parent Teacher Associations.

Chief executive David Butler said: "Primary pupils are over tested and the Government needs to address this issue immediately.

"Not only do Sats cause undue stress - particularly to seven-year-olds - but they also mean that children waste valuable lesson time preparing for Sats rather than having opportunities to broaden their educational horizons."

He added: "We urge the Government to listen to parents and rethink the future of Sats now. In particular, the Government should drop formal tests at age seven."

But a DfES spokesman said: "The reason we have testing is to fulfil the potential of every child.

"What parents want is for their own child to have their own individual talents developed. Testing helps teachers to do this."