Hungarian opposition MPs demonstrated a show of exceptional unity by taking an oath here on Thursday before the parliament to make 2019 "the year of resistance" against the Hungarian government.

"We swear to make 2019 the year of resistance, inside and outside the parliament, and we shall work in unity and cooperation with all of the opposition parties," the deputies swore on the stairs of the massive neo-gothic building of the Hungarian Parliament.

The adoption in mid December of the amendment of the labor law, referred to as "slave law" by protesters, sparked major protests against the government in the second half of December.

This controversial law, which brings to 400 the number of overtime hours that employers will be able to claim from their employees every year, but payment can be delayed by employers, does not diminish workers' rights, according to the government, which stressed that the overtime was based on volunteering.

But critics argue that workers have no leverage against their employers who might force them into working overtime.

The demonstrations, although failing to rally tens of thousands of people, seemed more persistent and organized than usual, and have spread to all parts of Hungary.

After their oath, opposition MPs also demanded the acknowledgment of their five points from the government, namely Hungary join the European Public Prosecutor's Office, the withdrawal of the law on labor, the removal of a recent justice reform that would hinder the independence of the judiciary, the independence of public media, and ultimately the reduction of overtime hours for police officers.

The oath of the opposition came as a major demonstration has been planned for Saturday, which is expected to unite people representing the opposition, trade unions, NGOs and even representatives of the Hungarians who have emigrated to western Europe in recent years.