Workers at Britain's state-owned Royal Mail have voted overwhelmingly for a nationwide strike, escalating a dispute over pay and conditions which has caused widespread disruption to postal services.

Members of the Communications Workers' Union voted by more than three to one in favour of the action on a 67 per cent turnout, although they left open the possibility of further discussions with Royal Mail to try to avert a walkout and full work stoppage.

Regional postal strikes in recent weeks have caused large-scale interruptions to postal deliveries, with a damaging impact on businesses. By law, union bosses will have to provide seven days' notice of a strike.

A spokeswoman for the union said notice would not be given right away as the union wanted to give Royal Mail a chance to respond to the strike threat. If executives do not respond, notice will be given early next week, she said.

Unions accuse the Royal Mail of introducing new working arrangements without consultation and say the new schedules have affected workers' pay and conditions.

The Royal Mail says its plans for greater automation are covered by previous deals with the union and says the new, modern methods are needed to better compete.

If a strike goes ahead, it would be the second national postal stoppage in two years.

With unofficial work stoppages around the country, a vast backlog of mail has already built up, a situation that threatens to worsen in the run-up to the busy Christmas postal period in 11 weeks.

Newspapers reported yesterday that online retailer Amazon was planning to cancel its contract with the Royal Mail as a result of the industrial action, but Amazon said that was not the case.

The British Chambers of Commerce said a nationwide strike could have a profound impact on business and the economy.

'This strike announcement defies logic at a time when businesses and government are working hard to move the UK economy back to growth,' Adam Marshall, the director of policy for the trade body, said.