PAU, the union representing workers employed by mail carrier Posti and the logistics firm Flexo, said Thursday that its members will be refusing to work overtime for two weeks, starting on Monday 24 September.
The overtime ban will affect all members working in the communications and information logistics sectors, PAU said in a statement Thursday.
PAU has joined several other employee organisations that have announced industrial action to protest government's plan to make it easier for firms with fewer than 20 employees to reduce payroll costs by sending workers home.
The government has said that it hopes that by making it easier for small firms to fire, it will lower the threshold for them to hire new staff.
In its statement, PAU described the proposed legislative change as an arbitrary termination law that would put some workers on an unequal footing merely based on the size of the employer.
Several other unions have also declared that they will undertake industrial action to protest the government's proposal. On Wednesday Jyty, the union representing public and private sector employees, said it would also join the resistance to the measure.
Last week, unions representing workers in the social and healthcare, practical nursing, public welfare, services and transportation sectors all announced bans on overtime hours and shift swaps.