Schools could face “severe” cuts of tens of millions of pounds if the government presses ahead with spending plans, union bosses claim.

In a list of areas which could be worst affected, released on Wednesday, the National Union of Teachers (NUT) and Association of Teachers and Lecturers (ATL) claim school funding across Newham will be slashed by £41.6m.

According to the unions, West Ham schools could lose £23m, equivalent to a cut of £837 per pupil per year by 2020.

And East Ham schools could face cuts of £18.6m with each student losing £786.

Both are within the top 25 areas which could face the most cuts, according to the unions.

West Ham MP Lyn Brown said: “Cuts by this government disproportionately hit Labour areas and thereby poorer areas of this country.

“It’s outrageous that the targeted cuts in education are now going to hit our children in the grossest way of all by impacting negatively on their schooling and their life chances.”

Stephen Timms, East Ham MP, said: “The unions are absolutely right to highlight the impact of this.

“It would have a very, very damaging impact after we have seen dramatic progress in raising school standards, which are now significantly above the national average.

“If we were to suffer the cuts in the unions’ model that progress would be seriously affected.”

Describing the results of their analysis as “startling”, union bosses called on the government to reverse its plan to cut funding per pupil in real terms.

NUT general secretary Kevin Courtney said: “Schools cannot continue to give the education children and parents expect and deserve unless additional funding is given.

“There is no further room to manoeuvre, budgets have already been cut to the bone and all the sacrifices have been made.

“Schools simply cannot take another blow to already precarious finances.

The spending cuts figures, based on union calculations which subtract projected funding figures up to 2020 from spending levels for 2015 to 2016, led unions to call on ministers to inject more money into “an already beleaguered system”.

But the government challenge the spending projections, questioning the formula unions used to produce them.

Commenting on the unions’ action, a Department for Education spokeswoman said: “This is irresponsible scaremongering based on speculation.

“It’s unfair and confusing for parents, pupils and schools.

“We are due to publish a new fairer funding formula, and as the NUT and ATL admit, their speculative figures do not take that into account.

“The government’s fairer funding proposals will ensure that areas with the highest need attract the most funding and end the historic unfairness in the system.”

The spokeswoman added it would be impossible for the unions to make such calculations until a new funding proposal was agreed on.