Workers began walking off the job yesterday to protest planned government reforms aimed at streamlining services and making the sector more efficient.
The unions say the government is imposing austerity measures that will cost thousands of jobs and cut services at a time when environmentally friendly public transport is essential.
Unions across Belgium originally sought a stage a five-day rail strike in January, but faced with consumer outrage cut the duration to two days. Unions in northern Belgium then withdrew from the strike.