Angry Greek farmers protesting falling subsidies began blocking the country's northern border with Bulgaria and Macedonia today, prompting a demand by Sofia calling on the European Union to intervene, dpa reported. Farmers, using their tractors, by evening had blocked some 20 key road links, including the main highway connecting the Greek capital Athens with the northern port city of Thessaloniki as well as two key crossing points to Bulgaria at Promahon-Kulata and Exohi-Ilinden. Motorists were forced to make detours to avoid adding three to four hours to the usual five-hour trip between Athens and Thessalonki. In Sofia, the Bulgarian government called on the EU Commission to take "immediate" action to get the border blockades lifted. Premier Bojko Borissov said on state television that if the border is not opened by Wednesday, then Bulgaria would demand compensation for each day the blockades continued. He said the situation was impermissible, with the Bulgarian economy "suffering major losses" from the Greek farmers' actions. "It shouldn't have to be that we must pay for the problems of a neighbouring state," he said, with his remarks coming amid reports that Bulgarian shipping companies feared losses running into the millions of euros. Earlier, Greek farmers' unions said they were determined to close off the main Bulgarian Kulata-Greek Promachonas border, as well as the Exohi border crossing at Drama and another crossing at Evros, refusing any trucks loaded with perishable goods to cross the border. The farmers are demanding more support from the Socialist government amid reduced EU subsidies and falling market prices. But the government is already under pressure from the EU to reign in its soaring budget deficit. The average income in Greece has declined by around a quarter over the past decade, according to farm unions. Farmers estimate that their income levels have declined by 25 per cent in the past 10 years. Most of Greece's farming sector is composed of small-scale farmers who rely on government handouts to survive. Last year, a month-long farmers strike triggered major problems for commercial truck drivers and travellers.