A teachers' boycott that would have thrown next year's primary school tests into disarray will not go ahead because not enough voted in favour of the industrial action, ballot results showed yesterday.

Although more than eight out of ten National Union of Teachers (NUT) members who voted were in favour, turn-out was too low to trigger the boycott.

Ministers and parent teacher associations were relieved but the NUT insisted the result was "no comfort" for the Government and vowed to press ahead with a campaign to get the tests for seven and 11-year-olds scrapped.

Complicated NUT rules meant that turn-out had to be above 50 per cent of the 100,000 teachers who were eligible to take part - and more than two-thirds of them had to vote Yes.

As the turn-out was 34.05 per cent, the industrial action failed to clear the first hurdle. Numbers voting Yes were 30,452, or 86.2 per cent, while 4,875 - 13.8 per cent - voted against the boycott.

The NUT is the largest teacher union and has a particularly strong presence in primary schools.

In primaries, where most of the staff belonged to the union, preparations for the tests next May would have ground to a halt.

NUT general secretary Doug McAvoy acknowledged parents would be relieved by the result of the ballot, which was held under the NUT's more restrictive rules than trade union law, which only requires simple majorities in industrial action votes.

Using the NUT rulebook would have enabled the union to reimburse members whose pay was docked during a boycott.

Mr McAvoy said: "There's there's no comfort in these figures for the Government.

"They identify the extent to which teachers are willing to rid themselves of something that they believe isn't supportive of their teaching, and therefore isn't supportive of the high quality of education they want their pupils to receive."

He vowed to enlist the support of parents, governors and other teacher unions in the anti-test campaign.

It received a boost when the National Confederation of Parent Teacher Associations (NCPTA) urged the Government to reform primary tests, officially known as Standard Assessment Tests .

Education Secretary Charles Clarke said: "We welcome this outcome. A boycott could have been very disruptive. It would have let down pupils and parents. National testing helps drive improvement in all schools."