The Communication Workers Union (CWU) says it wanted further negotiations after its members refused a 2.5% pay offer and voted heavily in favour of industrial action.

Union leaders are expected to set dates for a series of short stoppages later this week unless the deadlock is broken.

Seven days' notice will have to be given from calling a strike before the workers take any action.

The CWU wants an improved pay offer and a rethink on the Royal Mail's modernisation plans which the union claims will cost 40,000 jobs and lead to worse postal services.

A union spokesman said: "We will set out our case for a pay rise which matches inflation. We also want a deal on modernisation which has the acceptance of workers.

"We will ask the Royal Mail to step back from their current cost-cutting frenzy".

A Royal Mail spokesman said: "We have always said we are willing to meet with the union and explain what is on offer to them as well as the position the company is in."