Hugh Fearnley-Whittingstall has been criticising Morrisons / Rex Features

Dairy producers threaten supermarket blockade unless price cuts are reversed by end of month

Supermarkets have been called to a Government summit over plummeting milk prices as dairy farmers threaten to bring supplies to a standstill and blockade stores.

As the dispute escalated yesterday, the chefs Jamie Oliver and Hugh Fearnley-Whittingstall called for shoppers to boycott grocers who pay below the cost of production.

Mr Fearnley-Whittingstall told The Independent: "Those who want to make a statement in favour of dairy farmers should stop shopping at Asda, Co-op and Morrisons."

Last night hundreds of farmers using tractors blockaded milk processing plants in Somerset and Leicestershire.

The blockades at a Robert Wiseman plant and a Morrisons distribution centre near Bridgewater, Somerset, and outside an Arla plant in Ashby-be-la-Zouch, Leicestershire, involved more than 950 farmers, campaigners from the protest group Farmers for Action said. Protests and demonstrations were also reported in Leeds and Kent.

Supermarkets yesterday said the chefs should be attacking others who paid less for milk, such as food manufacturers.

Unless dairy processors reverse price cuts of 14 per cent imposed this summer by 1 August, farmers say they will destroy milk and blockade stores.Nigel Batten, a member of Farmers for Action, said: "These are peaceful protests but an ultimatum has already been issued that, if the milk price is not reinstated, we would be cutting off the milk supply. We feel we have got enough consumer and farming support to bring the milk supply to a standstill."

Processors Arla Foods have cut farmgate prices by 2p per litre (ppl), Robert Wiseman Dairies and First Milk by 1.7ppl and Dairy Crest by 1.65ppl, on top of 2ppl cuts earlier.

Farmers say the dairies have slashed their margins for supplying grocers. Marks & Spencer, Waitrose, Sainsbury's and Tesco pay a premium above the farmgate price. Others supermarkets pay premiums below the 30ppl it costs to produce milk.

In an attempt to break the deadlock, the Farming minister, James Paice, has invited supermarkets to a meeting. A spokesman for the Department of Environment, Food and Rural Affairs said: "He will be bringing in the supermarkets on Wednesday to see what more the supermarkets can do to support the industry."

Defra has been talking to dairies about establishing a code of practice that would allow farmers to walk away from contracts at short notice. Mr Paice said: "Government cannot and should not set prices but I will do everything in my power to get all levels of the supply chain to make the real changes needed to guarantee the industry's long-term future."

Mr Fearnley-Whittingstall said: "The culprits are mainly Morrisons, Asda – and the Co-op. What we are seeing is bully-boy tactics on price ."

Morrisons said: "We are curious why Hugh Fearnley-Whittingstall hasn't recommended boycotting users of milk outside the supermarkets who pay no subsidy whatsoever to farmers for milk."