Official figures show that Greece's economy shrank by 5.6 percent in the first quarter of the year, slightly worse than an initially estimated last month.

The Greek Statistical Authority reported the revised figure Friday, following its May 15 estimate of a 5.3 percent contraction.

The figures helped fuel debate over whether austerity measures are working following admission this week by the International Monetary Fund that it made mistakes in designing the country's bailout.

The conservative-led coalition government has promised a return to growth and international bond markets next year, arguing that the harsh austerity measures agreed in exchange for the bailout loans are finally working.

But the left-wing opposition on Friday demanded a debate in parliament on the future of the country's austerity measures in light of the IMF's report.