British farmers marched through central London on Wednesday in a colourful protest with sheep and cows draped in Union Jack, to demand government action against the sharp drop in food prices.

"All farmers are struggling to survive because the milk prices have dropped over 50 percent now," said Yulita Parkes, a member of Farmers for Action, the campaign group which organised the protest.

"Support Your Local Farmer", "Fair Trade for UK Farmers" and "Trust the Tractor" read placards held up at the march from Trafalgar Square past Prime Minister David Cameron's Downing Street office.

Around 1,000 farmers took part in the protest.

Overproduction of milk since EU quotas were abolished in April 2015 has triggered a collapse in prices across Europe and demands for support from farmers.

According to official data, the average revenue of British dairy farmers is set to fall by 45 percent this year to £46,500 (58,000 euros, $65,600) from the previous financial year.

England, Scotland and Wales currently have 10,500 dairy producers compared to 21,000 a decade ago, the agriculture ministry said, and campaigners warn that many more will be forced to give up due to the low prices.

Many farmers have also expressed concern about the possible loss of EU agricultural subsidies if Britain votes to leave the European Union in a referendum in June, although some say it could improve exports.

"We're not concerned about leaving the EU or staying in the EU. We will fight for our industry," said David Handley, another member of Farmers for Action.