“In as much as this is a spontaneous reaction, I think it’s a positive sign to express anxiety for the situation,” said Petalotis in a radio interview.

Finance Minister George Papaconstantinou said on state television that a “crushing majority” of Greeks had “real anxieties” about their future and that of their children.

Police estimate that about 20,000 people assembled in the Greek capital’s central Syntagma Square on Sunday, responding to calls on social networking sites for gatherings across Europe to demand “real democracy”.

Calling themselves the “indignants” and inspired by the thousands of demonstrators who have occupied Madrid’s Puerta del Sol square for over two weeks, young people also assembled in Paris, where about 1,000 young protestors gathered at Bastille square.