About 150 anti-capitalist "Indignants" who marched from France, the Netherlands and Spain, defied a ban to set up camp in a Brussels park Saturday to protest EU-ordered austerity measures.
The marchers, joined by Belgian protesters, arrived at Elisabeth Park in the rain by late afternoon, and started immediately to pitch their tents.
Belgian authorities said Friday they had banned the group from setting up camp there as the park had no running water.
The protesters have walked, some for months, from as far as Spain's Atlantic coast to converge on Brussels where EU leaders will stage a summit dominated by Europe's debt crisis on October 17-18.
Their aim is to hold a nightly alternative parliament in the park from October 8 to 15, modelled on Spanish protests and a similar gathering in central Athens' Syntagma Square, ahead of a big public rally on October 15.
The protesters said police deployed in numbers around the park since Saturday morning, with dog handlers, mounted police and a bus for mass arrests.
The mayor of the Brussels district of Koekelberg meanwhile suggested the protesters move into an empty building of the University of Flanders.
The group is likely to debate the possibility on Saturday night.
There have been clashes between police and Indignant sympathisers over recent months in Brussels, the European Union's capital, as well as in Spain and Greece.
Tension has risen over recent weeks with bigger battles between "Occupy Wall Street" demonstrators and New York police.