Thousands more post offices face closure if Royal Mail loses the battle to retain the Post Office card account (Poca) which pays out pensions and benefits to 4.5m people, the National Federation of Sub-Postmasters has warned.

In a letter to the prime minister, George Thomson, chairman, said sub-postmasters were becoming increasingly concerned about the government’s delay in awarding the contract to run the successor to the present scheme which ends in 2010.