The HSU told a news conference that the solution for the sustainablility of the second pillar would be to increase contributions for workers that are paid into that pillar by their employers.
The obligation to enter the second pension insurance pillar was imposed in 2002 on workers who were below the age of 40 that year.
HSU leader Silvano Hrelja said that the government had allowed too many benefits and reliefs for employers whom he accused of failing to take care about the social security of workers.
Hrelja also proposed that 120,000 pensioners, who were between 40 and 50 years old in 2002 and who voluntarily opted for the second pillar, now be offered the possibility to leave the second pillar.
He urged changing the current model of basic pension indexation.