Former Greek Prime Minister George Papandreou has announced the formation of a new party about three weeks before a snap national election on Jan. 25.

Papandreou unveiled the Movement of Democrat Socialists on Saturday in front of thousands of supporters.

Papandreou, the son and grandson of prime ministers, presented himself as a determined reformist against the old "corrupt" system that brought the protracted financial crisis to Greece. He led the PASOK party, founded by his father in 1974, from 2004 to 2012.

As prime minister from 2009 to 2011, he bore the brunt of the crisis and the onus of signing a bailout deal, which, although it prevented Greece from defaulting, is detested by many because the economy shrank by over a quarter and unemployment soared to record levels.