Royal Mail workers have begun voting on strike action after talks between bosses and the Communications Workers Union ended without agreement.

Union officials claim the current offer comes with too many strings attached, while Royal Mail chiefs have warned that any industrial action would be "commercial suicide".

Chief executive Adam Crozier claimed the CWU had "gone backwards" in its demands.

"We gained no sense whatsoever in today's talks that the CWU was prepared to be realistic or to countenance suspending its ballot for strike action to allow some grown-up conversation to take place," he said on Wednesday.

"On a whole host of issues the union if anything has gone backwards today to a point where, on a number of areas, it is asking for more money than it previously was and on this basis the talks have been suspended.

"We remain absolutely committed to coming to a sensible and realistic deal. When the CWU is ready to talk sensibly and realistically then we'll be ready to talk at any time."

Workers have been offered a 14.5 per cent pay deal over 18 months, say Royal Mail bosses.

But that figure is disputed by the trade union.

Officials argue the only guaranteed portion is a three per cent rise from October and a 1.5 per cent increase in April, both of which come with too many strings attached.

Royal Mail chairman, Allan Leighton, has written to staff members asking them not to back strike action.

"If you vote with the activists amongst the union against the deal - or don't vote at all - we begin the process of commercial suicide," he wrote.

The company wants to cut as many as 30,000 and scrap the second daily post in a bid to reduce its £750,000 daily losses.

Union bosses denied they were obstructing any deal between the two sides.

"It's quite clear that [the Royal Mail] came here with no intention of negotiating sensibly whatsoever and we will continue with our ballot on that basis," said spokesman Ray Ellis.

"They've treated the union with absolute contempt.

"We remain prepared to negotiate seriously when the business is prepared to do so."