Hundreds of farmers, hauliers and taxi drivers have blocked roads into Brussels, a day before an EU summit called to discuss ways to deal with the rising price of fuel.
Convoys of taxis and lorry drivers effectively closed parts of the Belgian capital's inner ring road on Wednesday triggering traffic chaos.
Police said they were braced for up to 1,000 trucks, tractors and taxis to arrive in the centre of the city.
The protesters, echoing recent demonstrations elsewhere in Europe and around the world, argue that the high cost of fuel is threatening their livelihoods.
They are demanding that European governments step in with subsidies to ease the impact of the soaring prices.
Around 200 tractors were seen driving towards the capital from the town of Courriere, 80 kilometres south of Brussels.
"The economic situation, agriculture wise, is not fabulous, as everybody knows," one farmer taking part in the protests said.
"This is why we are going to Brussels to show that we are against the OMC [open method of co-ordination] that the European commission is trying to vote through."
Police did not allow them to use the highways and redirected them onto local roads.
Costs increase
Global oil prices have quadrupled in the past seven years, hitting a new high of $139.89 a barrel during trading on Monday.
The high prices are pushing up costs across Belgium's economy, forcing shoppers to pay out more for groceries, power and transport, and eating into economic growth.
"It's becoming very, very difficult to make a living," Paul Delestiene, from the UPTR road hauliers' union, said.
"The diesel went up to about 40 per cent of our profit which is enormous considering the rest.
"The salary is the same and it's becoming difficult to buy vehicles, to work and most of all to retain your personnel."
Barricades were put up around the EU headquarters and about 800 riot police were on standby the day before leaders from the EU's 28 member nations gather for a two-day summit.
A similar protest by Spanish, French and Portuguese fishermen around EU headquarters two weeks ago turned violent, with windows smashed and cars overturned.