By Gary Eason Education editor, BBC News website, at the NUT conference

The NUT opposes classroom assistants taking lessons

The biggest teachers' union in England and Wales says more money is needed to avoid disruption in primary schools over teachers' workloads.

The NUT fears many teachers will not get the preparation time they are entitled to from September.

Head teachers say they cannot afford it. NUT leaders say they want to avoid industrial action.

But they say funding is the key and the government's advice - to resort to employment tribunals - is wrong.

In a further sign of divisions between the education unions on the whole issue - the second biggest classroom union, the NASUWT, has said it does not agree with the NUT.

Strike call

From the autumn term, teachers are due to get half a day each week out of lessons for planning, preparation and assessment.

The secretary of state is suggesting a remedy that doesn't exist Steve Sinnott

The government says the funding has been made available for this.

But the National Association of Head Teachers has said many of its members cannot afford the changes, and has pulled out of the national workload agreement.

The general secretary of the NUT (National Union of Teachers), Steve Sinnott, said his members felt the same way.

A resolution at their annual conference this weekend calls for "nationally co-ordinated industrial action to secure the funding needed", including a one-day strike.

Funding

Mr Sinnott said schools across England and Wales identified this as a funding issue and there was time to head off the prospect of disruption to children's learning.

It's quite bizarre of a trade union to try to challenge and undermine a secretary of state who is trying to enforce contract changes that are of benefit to teachers Chris Keates

"We should use the summer term with the secretary of state to properly assess the funding that's necessary for each and every school to deliver that entitlement," he said.

But his counterpart at the National Association of Schoolmasters Union of Women Teachers (NASUWT), Chris Keates, said plenty of schools had been able to implement the agreement within their budgets.

Head teachers who had claimed they could not afford it had, when challenged, not come forward to be shown how to do it, she said.

Legal challenges

The Education Secretary, Ruth Kelly, said this week she hoped local education authorities would sort out any cases where teachers did not get their preparation time.

But otherwise "the normal route" would be to get an industrial tribunal to order a resolution.

The NUT's Graham Clayton says the issue is how to enforce entitlement

Mr Sinnott, said: "The secretary of state is suggesting a remedy that doesn't exist."

NUT solicitor Graham Clayton said employment tribunals could issue "statements of main terms and conditions" clarifying people's job contracts.

"But we won't get disputes about that. We know that the contracts contain the entitlement to preparation, planning and assessment.

"The issue will be - as Ruth Kelly appears to have identified it - how to enforce the entitlement."

And that would involve more complex and expensive court action.

Ms Keates disagreed with the NUT on this issue too.

She said she would be unveiling at her conference next week a package of legal remedies open to teachers - including tribunals as well as the courts.

She thought the NUT had "lost the plot a bit".

"It's quite bizarre of a trade union to try to challenge and undermine a secretary of state who is trying to enforce contract changes that are of benefit to teachers."