Independent retailers underlined their commitment to rural post offices this week as a national campaign calling on the government to protect the post office network reached fever pitch.

The National Federation of Sub Postmasters presented Tony Blair with a petition of four million signatures on Wednesday. Subpostmasters presented their case to MPs throughout the day. The prime minister has ruled out further subsidies for the Post Office, but promised existing subsidies of £150m per year would continue.

A spokesman for the Association of Convenience Stores said: "We are supportive of the NFSP's overall drive. Like local shops, post offices are vital to local communities and in many areas the two are the same."

Paul Taylor, general manager, marketing for Martin McColl, which operates 332 c-stores and 945 newsagents, said: "We are fully committed to the service post offices provide within neighbourhood stores. If space allowed, we would have one in every store."

Kelvin Ling, head of sales support for MBL, said: "We support subpostmasters because we have a number of stores that have subpostoffices." Londis alone has 400 stores with subpostoffices.

Geoff Hallam, MD of The Grocer Top 50 retailer Tates and a subpostmaster himself, said: "We have 52 subpostoffices in stores and we think they have an important role to play in the community."