Schools face a perfect storm of rising costs and real terms cuts, parents are warning.

A new campaign group, led by mothers and fathers, says Government plans for a new national funding formula are a smokescreen and ministers must invest more in all of England's schools.

The call comes as education unions said figures show that every parliamentary constituency in England will see schools face funding cuts in the next few years, more than £1,000 per pupil in some cases.

The Department for Education said the figures were fundamentally misleading.

Jo Yurky, co-founder of the Fair Funding For All Schools campaign officially launching on Tuesday, said: "There's a perfect storm coming together of rising costs, rising numbers and real terms cuts, plus the bringing about of the national funding formula."

She said more investment is needed in all schools instead of rearranging funding through a new formula .

A petition will call for adequate funding for all schools, and campaigners plan to hold days of action.

The proposed new national funding formula announced by Education Secretary Justine Greening in December increases money targeted at schools with additional needs including deprivation.

The changes, introduced from 2018 to 2019, will mean more than 10,000 schools gaining funding, it has been suggested.

But an analysis of Government figures by six unions concludes that funding plans will affect all 533 parliamentary constituencies in England.

The unions previously said 98% of schools face a real terms funding reduction for every pupil, with an average loss of £339 per primary pupil and £477 for secondary students.

The department's schools budget is protected in real terms but does not provide for funding per pupil to increase in line with inflation.

A National Audit Office report published in December warned that schools could face a real terms funding drop of £3 billion over the next few years.

This threatens the introduction of a new national funding formula, the unions said, arguing that while a new formula can address funding disparities, the initial total budget must be large enough.

NAHT general secretary Russell Hobby, said: "The Government's £3 billion real terms cut to education funding must be reversed or we will see education and care suffer.

"Already heads are being forced to cut staff, cut the curriculum and cut specialist support.

"A new funding formula is the right thing to do, but it cannot be truly fair unless there is enough money to go round in the first place."

A Department for Education spokesman said: "School funding is at its highest level on record and will be over £40 billion in 2016-17.

"Under the proposed national schools funding formula, more than half of England's schools will receive a cash boost in 2018-19.

"This will help to create a system that funds schools according to the needs of their pupils rather than where they live - disparities in the current school funding system mean a school could get 50% more if it were situated in another part of the country."