Thousands of people gathered in central Athens to protest against the latest round of austerity measures approved by the Greek government and its European creditors.
The parties have agreed to resume talks on new reforms to the tax system, pensions and labour laws.
Once the review is complete, Greece will be able to access the next installment of its bailout funds, which it needs to meet a 7 billion euro (7.4 billion US dollar) debt repayment in July.
But the demonstrators say the poorest will suffer most.
The demonstration, organised by the Greece Communist Party’s union PAME, began with a short rally at Omonia Square and ended in front of the Parliament building in Syntagma Square.
Panayotis Petrakis, Professor of Economics at the National University of Athens, said: “There are negative consequences to the whole of the Greek economy from the delay of the review.
“We should by all means complete the negotiations with the creditors as soon as possible in order to bring hope to the people as well as to attract investment from abroad.”