Planned Government reforms to the way schools are funded risks creating another generation of "winners and losers" in the classroom, a teachers' union has said.

The NASUWT has said the shake-up of funding proposed in the Government's white paper Education Excellence Everywhere is causing "further anxiety" for schools after what it claimed were years of cuts to school budgets.

On Saturday, Education Secretary Nicky Morgan told the union the reforms would "put an end to the antiquated system of school funding which saw so many young people miss out on resources because of an unfair postcode lottery".

Speaking on the last day of the NASUWT annual conference in Birmingham on Monday, general secretary Chris Keates called for more detail to be released on how the new funding rules would help individual schools and how moving to the new system would be managed.

She said: "As a result of the Government's failure to protect school budgets in real terms, jobs have been lost, vital support services on which schools rely have been scaled back or withdrawn altogether, and the range of educational options for young people have been curtailed.

"Now, schools are facing further anxiety as a result of the Government's plan to revise the national school funding formula.

"Given the Government's track record of cuts to school budgets and at a time when further austerity measures are being planned, the NASUWT is concerned that the revised funding formula is likely to create winners and losers, with the consequent impact on children's education.

"Diminishing further the role of local authorities is also likely to make it more difficult to deliver additional support to schools when they need it."

She added: "A funding system for schools that is capable of recognising local needs and circumstances and which is democratically accountable must be the best way to ensure that the needs of children and young people across very different contexts and circumstances are met.

"The NASUWT believes that any change to the funding system must enable all schools to continue to deliver the best possible education for their pupils."

In a wide-ranging speech to conference at the weekend, Ms Morgan outlined the wider white paper reforms and told delegates there was "no reverse gear" to the changes, urging teachers to "step up" and work with the Government.

She said: "The white paper outlines our plan for a new national funding formula for schools.

"We want to put an end to the antiquated system of school funding which saw so many young people miss out on resources because of an unfair postcode lottery.

"So, we are delivering on our commitment to put in place a fairer formula for schools and for allocating high-needs funding to local authorities, for both special needs and alternative provision.

"We believe this is central to achieving education excellence everywhere.

"Because it must be right that the same child with the same costs and the same characteristics attracts the same funding - that is just basic fairness.

"The formula itself will contain a significant weighting of disadvantage-funding."

She added: "On top of that we are also committed to the pupil premium, so that pupils from disadvantaged backgrounds can get the extra resources they need - and we want schools to use evidence to advance its effectiveness.

"Our aim is to move 90% of schools onto this new formula by the end of this parliament, so that schools are not kept waiting for the funding they deserve."