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 Barking and Dagenham will be slashed by £22m.

According to the unions, Barking schools could lose £13.8m, equivalent to a cut of £602 per pupil per year by 2020.

Dagenham and Rainham schools could face cuts of £8.5m with each student losing £528 over the same period.

Barking MP Margaret Hodge said: “Ensuring our young people get a first-rate education so they can reach their true potential is vital.

“These constant cuts to education from this Government puts this at risk.

“We need more school places, more funding and top quality teachers, so that children in the borough get the education they deserve.”

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.

Dominic Byrne, Barking and Dagenham NUT branch secretary, said: “These cuts are going to be damaging.

“Things here are improving so what the government should be doing is increasing funding.

“Because of the cuts there will be fewer subject choices. There will be less individual attention for students. There will be early years and special educational needs spending cuts.

“Teachers and support staff will be cut or not replaced when they leave.”

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 cuts figures are based on union calculations which subtract projected funding figures up to 2020 from spending levels for 2015 to 2016.

But the government challenge the unions’ spending projections, questioning the formula they 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 spokewoman added it would be impossible for the unions to make such calculations until a new funding proposal was agreed on.