We were under the impression that it was the Ministry of Agriculture, and not the supermarkets, which set agri-policy in this country

Asda spokesman

He said he would be speaking to farming and supermarket leaders to discuss the way forward for the industry in the wake of the foot-and-mouth crisis.

But Asda spokesman Nick Agarwal said: "We are too busy working for our customers to pay much attention to what Tony Blair said.

"If he 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."

'Extremely concerned'

Other major stores also defended their relationship with suppliers.

A spokesperson for 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."

We very much welcome discussions with government on how such situations can be avoided in the future

Sainsbury's

She added that Tesco has been "working closely" with its suppliers to support them through the crisis.

Mike Glover, a spokesman for Sainsbury's, said: "We are extremely concerned about the current situation. It is not good for our customers, our suppliers, nor our business.

"Our primary responsibility is to our customers but we have very solid allegiances to our predominantly UK suppliers, with whom we have built up strong relationships over a number of years.

"We very much welcome discussions with government on how such situations can be avoided in the future."

'Sustainable farming'

Mr Blair made his comments as he addressed Labour party supporters, including farmers, at Hartpury Agricultural College, Gloucestershire, on Thursday evening.

He said: "We all want cheaper food in our shops, but on the other hand the supermarkets have pretty much got an arm-lock on you people at the moment.

"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."

The relationship between farmers and supermarkets is under scrutiny

Later, a spokesman for the prime minister insisted that Mr Blair was not trying to scapegoat the supermarkets.

"It is ludicrous to suggest, as some are seeking to do, that the prime minister was in some way blaming the supermarkets for foot-and-mouth," the spokesman said.

"He believes the supermarkets are playing an important role during the current outbreak."

The Food Standards Agency and the National Farmers' Union have both said the time is right for a debate.

Code of practice

Although a recent competition commission investigation gave supermarkets a clean bill of health, it did have reservations, Downing Street has said.

It found that small suppliers such as farmers bore a disproportionate burden of costs because of the supermarkets' buying power.

It is ludicrous to suggest that the prime minister was in some way blaming the supermarkets for foot-and-mouth

Prime minister's spokesman

The Office of Fair Trading is considering setting up a new code of practice outlawing some methods used by supermarkets to pay farmers less.

These might include the practice of fining farmers when their goods do not meet acceptable standards.

The code has been out for consultation between farmers and the industry for the last two weeks.

The spokesman did not accept that doing something about the "arm-lock" would mean higher prices.

He added that what Mr Blair wanted was an open and transparent relationship between supermarkets and suppliers.