The Communication Workers Union is set to ballot members on strike action next week after rejecting a 14.5 per cent pay deal tied to shift changes and productivity targets.

The union has revealed that it would not accept wider proposals to reduce the 200,000-strong workforce with 30,000 voluntary redundancies.

"We will not do this," said Dave Ward, the union's postal deputy general secretary. "It would be signing the death warrant for the entire postal service."