Launching the event, prime minister Tony Blair urged shoppers to look out for the Red Tractor logo, which assures that UK products are produced, processed and packed to independently inspected standards.
He also urged more UK food businesses to join up with the scheme, which is run by Assured Farm Standards.
Blair said: “Last year it appeared on more than £5bn worth of food. This demonstrates what can be achieved by farmers, processors and retailers working together.”
He added: “I hope that the success of the Red Tractor will encourage other food businesses to join the alliance.”
The National Farmers' Union pledged its support to the scheme. Peter Kendall, president of the NFU, said: “We need to differentiate British produce from the imported competition on the basis of our very high standards, and the Red Tractor is crucial in enabling us to do that.”