Theresa May is planning to plough billions of extra pounds a year into health spending as part of a “birthday present” to mark the 70th anniversary of the NHS.

Senior government sources say the prime minister will overrule the Treasury and boost spending to tackle growing waiting times and neutralise Labour’s political trump card.

The announcement, scheduled for July, is expected to lead to up to £4bn extra annually for the health service over the next 10 years. A special NHS tax is “still on the table”, a cabinet source said.

The new money will kick in from next spring, as Britain leaves the European Union, allowing ministers to argue that the government has begun to fulfil the pledge of Vote Leave that £350m a