Dozens of areas across Greece, including the capital Athens, suffered blackouts on Thursday as union workers continued strikes over pension reforms.
In many areas the power cuts lasted for more than two hours, as the walkout shut down 16 power plants, earthtimes.org reported.
Workers protest over proposed pension reforms, which aim at increasing retirement age and merging dozens of pension funds into five to eight main funds.
PM Costas Karamanlis declared Greece had no choice but to change its complicated and outdated pension system, as the state is currently spending about EUR 24 B a year, which amounts to 12.5 percent of its GDP, to fund payments to retired Greeks.
According to the conservative government, the pension system runs the risk of going bankrupt in 20 years because of an aging population and low birth rate.