Police have been pelted with petrol bombs in Athens as Greece passed unpopular tax and pensions reforms.

Thousands of protesters took to the streets ahead of a vote that the government hopes will unlock bailout cash and pave the way for progress on debt relief when Eurozone finance ministers meet today.

The demonstrations outside parliament in the capital and in Thessaloniki were largely peaceful, but small groups of protesters attacked riot police, who responded with tear gas.

Inside the parliament building, Prime Minister Alexis Tsipras survived a crucial test of his wafer-thin majority, as all 153 of the ruling coalition's lawmakers in the 300-seat parliament voted in favour of the changes.

The reforms will reduce some pension payouts, merge a number of pension funds, increase social security contributions and put up taxes for middle and high earners.

The measures have been deeply unpopular with anti-austerity campaigners and trade unions, but Mr Tsipras argued they would not affect most pensioners and moved the country towards a "sustainable" system.

"We have an important opportunity before us for the country to break this vicious cycle, and enter a virtuous cycle," he told lawmakers.

But he came under attack from opposition leaders, who accused him of betraying voters who re-elected his government last September on promises to ease the pain of austerity and protect pensions.

"Mr Prime Minister, you promised hope and turned it into despair," said Fofi Gennimata, leader of the opposition PASOK socialists.

"The measures will be a tombstone for growth prospects," said Kyriakos Mitsotakis, leader of the conservative New Democracy party which leads in opinion polls.

The package aims to generate savings equivalent to 3% of GDP, raising income tax for high earners, lowering tax-free thresholds and increasing a so-called "solidarity tax".

More taxes could be in the offing, with newspapers reporting on Monday that Greece plans to increase VAT and introduce additional taxes on fuel and tobacco, overnight hotel stays and internet use.

Eurozone finance ministers will meet later to discuss Greece's reform progress and whether it has met the terms of a multi-billion-euro bailout.

A positive outcome will see more than €5bn released to ease Greece's financial burden and allow it to make debt repayments in June and July.