The Transport Workers' Union (AKT) announces an overtime work stoppage for several of its industries beginning on Monday.
The AKT says the motivation for the overtime strike is political and specifically targets the Finnish government's plan to make it easier for companies of less than 20 employees to fire their workers.
The transport union's ban affects trucking, bus conductors, bus station enterprises, car repair shops and road tanker transport.
The AKT says the overtime ban will be in place until the end of September.
The union's board says it intends to meet in early October to reassess the situation, and possibly extend the strike.
"Other organisational tactics are also at the disposal of the labour market as anti-governmental measures should the situation call for them," the AKT writes in its release.
On Wednesday the Industrial Union (for industry employees) and Trade Union Pro (for industry officials) announced their plans to introduce an overtime ban on Monday, 17 September.
SAK, the almost million-member-strong union confederation, is also preparing counter action against the proposed measure.