Head teachers have written to Theresa May to warn that a funding crisis could make schools reduce hours, lay off staff or stop teaching some subjects.

The letter to the prime minister has been signed by the heads of every state school in West Sussex, who argue they need £20m in emergency funding.

They say the "distraction" of grammar schools cannot be a priority ahead of basic funding and staffing.

The government has promised a complete overhaul of school funding in England.

But the plans for a national funding formula, which would address inequalities in school funding, have been postponed.

'Dire financial position'

The head teachers, from more than 250 primary, secondary, special schools, academies and local authority schools in West Sussex, say that without £20m emergency transitional funding, ahead of the funding formula, they will have to make cuts.

A group of pupils and head teachers will go to Downing Street on Tuesday to deliver the letter, which is also being sent to more than 100,000 West Sussex parents.

The lack of progress on funding, they say, has meant "a crippling effect on our already dire financial position".

The head teachers have told the prime minister that without extra funds there will be cuts to schools from next spring.