Protesters in Greece have clashed with riot police as MPs prepare to vote on a fresh round of austerity measures to secure the next round of bailout funds.

The police fired tear gas towards the protesters when they were attacked with petrol bombs in the capital Athens.

Parliament is due to vote on 13.5bn euros ($17.3bn; £10.5bn) of measures, including tax rises and pension cuts.

PM Antonis Samaras said without the bailout Greece would run out of money this month and face "catastrophe".

The fresh package of austerity measures - Greece's fourth in three years - is meant to close Greece's budget deficit, lower its huge debt burden and make its economy more competitive.