Greece's statistical agency says unemployment in the crisis-struck country has risen to a startling 23.1 per cent in May - up from 16.8 per cent a year earlier.

An agency statement said the worst affected group is young people under 25, where 54.9 per cent are out of work.

A total 1.15 million people were unemployed in May 2012, compared to 1.1 million in April, or 22.6 per cent of the workforce.

In May 2009, months before Greece's crisis broke, unemployment was just 9.1 per cent.

Greece has avoided going bankrupt by international rescue loans.

In return, Athens has imposed harsh austerity measures to limit runaway government overspending and improve chronically weak tax revenues.