Belgium faced growing disruption on Tuesday after staff at schools, city transport networks, airports and government offices received calls to join striking railworkers and prison guards.
The socialist CGSP union urged public service workers to stop work for 24 hours from Tuesday to protest the centre-right government's austerity plans, including raising the retirement age.
Pickets will disrupt city train, bus and tram services as well as schools and government offices, CGSP spokesman Pierre Vermeire told AFP.
Air traffic controllers and workers at the northern port city of Antwerp will also strike, he added.
Inter-city rail workers on strike since last week and prison staff who stopped work five weeks ago meanwhile vowed to continue their walkout in Brussels and the southern French-speaking region of Wallonia.
Nearly 95 percent of prison staff in those regions on Monday rejected as insufficient a proposal made last week by Justice Minister Koen Geens to increase personnel, the GCSP said.
The CGSP and the Christian SSC/ACV union on Monday meanwhile rejected offers from the state-run SNCB railway firm aimed at ending a strike launched May 25 over reductions to overtime compensation.
Growing worker discontent in Belgium comes amid mounting unrest in neighbouring France over contentious labour reforms.
After attempting to paralyse France with blockades of refineries and fuel depots last week, the hardline CGT union has responded by calling for strikes on the national rail network beginning Tuesday and on the Paris Metro from Thursday.
Air travellers are also set to face more cancellations and delays.
Last Tuesday, Belgian police fired water cannon at protesters on the margins of a demonstration in Brussels against the government's austerity plans, leaving 10 people injured.