Countryside campaigners have warmly welcomed Tony Blair's promise to bring long-term changes to UK's farming industry.

Speaking on Thursday night in Gloucester the prime minister pledged to meet with supermarket bosses and farmers' leaders once the foot and mouth crisis has been resolved. He wanted change on types of farming, diversification and better marketing of produce.

Blair said to a group of farmers that supermarkets had "pretty much got an arm-lock on you people at the moment". He called for a re-think on the way Britain produces its food. "I think we need to sit down with the industry and really work out what is the basis on which we want sustainable farming for the long-term. And in a sense, what price are we all prepared to pay for that as well."

Nigel Henson of the Countryside Alliance welcomed Tony Blair's new stance. "It would be extraordinarily churlish not to say we are pleased to have the support of the prime minister. We will be pleased to work with the government to bring about progressive change. It's just sad that it has taken a disaster of this scale to focus the government on recognising what we've been saying for the past three years. We need a complete overhaul of the farming industry."

Henson pointed to two areas where the government had failed farmers. "The campaign to save rural abattoirs should have been heeded. The legislation that affected them was passed before the government came into power but it could have been looked at."

"The supermarket pricing investigation was another missed opportunity. It reached an extraordinary conclusion that there was no pressure on farmers based on comparison with Europe. It does not take the brains of Einstein if you look at the prices of produce leaving the farm gate," he said.

Supermarkets reacted angrily to Blair's new pro-farming stance. A spokesman for Asda, Nick Agarwal, said: "If the prime minister wants to play politics and scrabble around looking for scapegoats then that is down to him. We were under the impression that it was the ministry of agriculture, and not the supermarkets, which set agri-policy in this country."

Tesco said: "We are surprised by the prime minister's comments and we are currently seeking further clarification. We have a very good working relationship with our suppliers - we are the number one customer of British farmers."