Mail deliveries are expected to be crippled as the first 24-hour national strike by postal workers in over a decade begins. Up to 130,000 members of the Communication Workers Union will take action from the start of 3am shifts after dismissing a 2.5 per cent pay offer and warning that the Royal Mail's modernisation plans will lead to 40,000 job losses. A final attempt at talks aimed at breaking the deadlock failed on Wednesday evening, leading to warnings that the strike would damage the postal organisation and boost its competitors. Picket lines will be mounted outside sorting and delivery offices, while managers will be called in to cover for striking workers at Crown Post Offices. The strike will go ahead less than two days after Gordon Brown took over as Prime Minister, giving his new-look Government an early test of how to deal with a big public sector dispute. CWU deputy general secretary Dave Ward said: "What Royal Mail are doing is not modernisation. The truth is, they are intent on cutting services, cutting jobs and cutting pay." He continued: "We have tried to reach an agreement but Royal Mail are refusing to negotiate." Further strikes will be called if the deadlock is not broken, which the union said would have maximum impact on Royal Mail at minimum cost to workers. Mr Ward rejected complaints that strike action would damage Royal Mail and said it was the company's modernisation plan which was hitting postal services. He said: "The reason Royal Mail is losing work to competitors is that they are running away from competition. "The real reason they are losing work is their own mismanagement. They can afford a decent pay rise." Royal Mail said the strike would only add to the "very difficult competitive challenges" the organisation was already facing. The union is demanding that postal workers' pay should rise to the national average over the next five years, which the Royal Mail said amounted to a 27 per cent increase. The union is also campaigning to prevent the Royal Mail closing 70 larger post offices and move services into WH Smith stores.