Company officials, led by chief executive Adam Crozier, met leaders of the Communication Workers Union in a bid to break a deadlocked dispute over pay and modernisation.

The union has rejected a 2.5% pay offer and wants the Royal Mail to change its modernisation plans which it claims will lead to 40,000 job losses.

Up to 130,000 union members will stage a 24-hour walkout on Friday, crippling mail deliveries across the UK.

The Royal Mail said its officials again went through the business plan with the union and explained the reality of the commercial pressures it now faced.

A spokesman said: "We explained again the need for Royal Mail to modernise just as all our major rivals have already done if we are to compete for business in an increasingly tough marketplace.

"Royal Mail is already losing business because we have not yet modernised and therefore our prices are higher than those that rivals are charging in the intensively competitive business mail market.

"Unfortunately we were unable to reach agreement and it now looks inevitable that the union will go ahead with a strike on Friday although we remain available to meet with them at any time.

"Royal Mail is extremely disappointed that the union has failed to grasp how damaging a strike will be for our customers, our people and the company."

The industry's watchdog, Postwatch, has urged people not to send any mail on Thursday and Friday because of the strike.