Britain's network of sub post offices is in serious danger of extinction, the Government has been warned.

The National Federation of Subpostmasters said that urgent Government action was now needed to prevent the network sinking into terminal decline.

The federation set out its proposals to revitalise the system in a manifesto, launched at Westminster with the backing of the all-party post offices group of MPs.

It called for a one-off cash injection of £150 million for the urban network to produce bigger, better and brighter post offices, while drawing up a programme by 2008 to develop the optimum, viable rural network.

It said the current level of Government support was doing no more than prop up an ailing rural network and that start-up cash was need for refurbishment and the ongoing provision of social and economic services.