More than 300 dairy farmers in Belgium have blockaded supermarket depots, angry at the price they get for their milk.Warehouses supplying several chains, including the low-cost German stores Aldi and Lidl were brought to a standstill, with hundreds of trucks allowed neither in nor out. The knock-on effect of the action also paralysed several main roads. A representative of the farmers warned there was a strong possibility the protests would be prolonged, because he said the bosses of the big chains had not reacted to the demands of the producers. Farmers say supermarkets are threatening their livelihoods by using their massive buying power to force down the price of milk. One chain said its shops might also run short of meat and fruit and vegetables over the next 48 hours because of the disruption.