(NewsNation) — Greece on Monday introduced a six-day working week for some businesses in an effort to increase productivity.

Prime Minister Kyriakos Mitsotakis‘ government said the overhaul would eliminate undeclared work and boost employment overall, but labor unions and the opposition say it is an assault on workers’ rights and would create barbaric conditions.

The law allows full-time employees to get a part-time second job and work up to 13 hours a day unless certain terms apply, such as a conflict of interest. It also enables employers to implement the six-day working week.

Thousands of Greek public sector workers, including teachers, doctors and transportation staff, marched in Athens last week during a strike against the law.

According to CNBC, Greek employees were found to have worked an average of 1,886 hours in 2022, more than the U.S. average of 1,811 and the European Union average of 1,571.

Greece’s controversial move comes as many countries are taking a closer look at a four-day workweek.

U.S. lawmakers in March reintroduced a bill in Congress to create a four-day workweek as experts tout its effectiveness in improving businesses and the lives of its employees.

A trial of 33 companies employing 1,000 people across the U.S., Ireland and Australia tested the four-day, 32-hour workweek as part of a six-month pilot program. By the end, not a single participating company reported wanting to switch back to the standard workweek.

Employees who were part of the trial cited an improvement in stress, burnout and work-life balance. The companies also saw a revenue increase of 8% during the trial period.

A trial of a four-day workweek in Britain had similar results, with 61 participating companies reporting happier employees.

NewsNation’s Urja Sinha and Reuters contributed to this report.