Athens - Thousands of farmers blocked border crossings and all major highways across Greece Monday for the eighth straight day in a showdown with the government over falling commodity prices.

Thousands of tractors blocked the Greek-Macedonian border at the Evzonoi and Doirani crossings. The farmers also blockaded borders with Bulgaria and Turkey where freight traffic has been paralysed and only emergency medical supplies were allowed to pass.

The blockades have sliced the country in half, with farmers occupying key junctions along the Athens-Thessaloniki highway and other roads in northern Greece.

They planned to ratchet up the protest by blocking the bridge connecting the Peloponnese peninsula and Corinth on Monday, after talks with the government failed, despite promises of relief totalling 500 million euros (650 million dollars).

Greek Prime Minister Costas Karamanlis said the government did not have the means to improve on its aid offer.

The farmers are demanding an increase in government subsidies and pensions after incomes dropped by almost one quarter in the last 10 years, owing to shrinking EU grants and falling commodity prices.

"We are not leaving until the government meets our demands, we need precise details about subsidies per hectare," Farmer Union leader Gerasimos Kalimaris told Flash radio.

The blockades caused several kilometres of traffic jams as thousands of trucks were prevented from leaving the country. There were reports of farmers clashing with truck drivers whose loads of meat and produce lay rotting.

Over the weekend, truck drivers could be seen burning meat at various northern border crossings to protest the blockades.

Tractors were also deployed along the highway which connects the cities of Hania and Irakleio on the southern Mediterranean island of Crete.

Producers say they are particularly upset about the plummeting prices of cotton, corn and wheat, which are set by the European Union, and claim that they are struggling to make a living.

The Association of Northern Greek Industries urged the government to resolve the strike quickly, saying it was hurting a manufacturing sector that was already suffering from falling demand for exports and a dockworkers' strike.

A similar protest in 1997 also ended up cutting Greece in two for several weeks, forcing the Socialist government, then in power, to sabotage the tractors by puncturing their tires. (dpa)