Farmers across Britain are being urged to withhold their produce from sale on Friday to highlight falling incomes in the industry.

Agricultural lobby group Farmers For Action (FFA) is behind the move which could see supermarkets running out of milk and other perishable goods over the Bank Holiday weekend.

But the National Farmers' Union has criticised the action, saying it could do more harm than good.

Meat will also be withheld

The FFA has called on farmers to suspend food deliveries for 24 hours in an attempt to draw attention to a deepening crisis facing Britain's rural economy.

It says 70,000 farmers are planning to take part, and has warned that supplies of some fresh products, particularly milk, will be affected.

It is calling on farmers not to sell any produce during the day - even if it means it goes to waste.

'Myth'

David Handley, the group's leader, rose to prominence in the fuel crisis of autumn 2000.

As head of the People's Fuel Lobby he masterminded a blockade of petrol refineries which nearly paralysed the UK economy.

Intended as a protest against rising fuel taxes, the blockade choked off most of the country's fuel supplies, disrupting commercial deliveries and cutting motor traffic in half overnight.

Farm strike leader David Handley

The FFA wants the government to set up a watchdog to help farmers get better prices from supermarkets, their main customers.

Mr Handley said: "There's an impression given that supermarkets are looking after the farmer and the consumer, but it's a myth. They are profiteering on the back of both of us."

The FFA has previously threatened to blockade supermarkets' distribution centres in protest over aggressive price bargaining.

The supermarkets deny charges of exploitation, saying they are merely responding to market forces.

Kevin Hawkins, a spokesman for Safeway, also denied that the supermarkets are making huge profits.

"The margin we make on milk and many other commodities is very low indeed," he told BBC Radio 4's Today programme.

"We had a Competition Committee inquiry into supermarket profits two years ago which said that our profits are not excessive and that we are competitive."

'Extremely risky'

Meanwhile, the mainstream National Farmers' Union, the country's biggest farm lobby, has advised its members to play no part in the strike.

"We think this is an extremely risky strategy that could seriously backfire," the NFU said in a statement.

"Such action could damage the relationship between individual farmers and their buyers, and lead to long-term financial losses for the farmer concerned."

The NFU argues that in the current climate, farmers should hold onto whatever sources of income they have left.

Last month, the organisation calculated that farm incomes have fallen by over 70% since 1995.

It says the average British farmer now earns about �10,000 a year - less than the minimum wage.