BRUSSELS (BELGIUM): Police fired tear gas and water cannon at some of the tens of thousands of people who took to the streets of Brussels on Thursday, as a nationwide strike against the new Belgian government's austerity measures grounded planes.

Flemish nationalist Bart De Wever took office as prime minister on Feb 3 after months of coalition talks following Belgium's elections in June last year.

But trade unions have been incensed by his push for pension reforms as Belgium gets to grips with a budget deficit whose size violates EU rules.

De Wever has vowed to rein in spending as Belgium faces potential sanctions from the European Union if it fails to take effective steps to address the ballooning deficit.

Protesters in Brussels held placards saying: "We're not lemons", "When will we tax the rich?" and "Stop fleecing us", reflecting concerns at the rising cost of living.

AFP journalists saw police use water cannon and tear gas against some masked protesters, who threw objects including a fire extinguisher at the officers, outside the headquarters of one of the coalition government's five parties.

According to Brussels police, there were "several arrests" at the protest, which it said 60,000 people took part in.