Greek trade unions marked May Day on Monday with a 24-hour nationwide strike and protests against looming new cuts demanded by the country's creditors in return for bailout cash.
Some 10,000 people demonstrated in Athens while another 3,500 marched in Thessaloniki, police said.
The strike, on a public holiday in Greece, saw businesses shuttered, ferries and trains suspended, and a state services shutdown.
"We must take back all that was stolen from us during the crisis," said Communist party leader Dimitris Koutsoumbas.
"We must scrap all anti-labour laws...and unilaterally erase the (Greek public) debt," he said.
A general strike will be held against the cuts on May 17.
"Bailout government and the creditors have been squeezing the people and workers for seven years," said civil servants' union Adedy.
Under pressure from its creditors -- the European Union, European Central Bank and the International Monetary Fund -- the government agreed earlier this month to adopt another 3.6 billion euros ($3.8 billion) in cuts in 2019 and 2020.
Athens conceded fresh pension and tax break cuts in return for permission to spend an equivalent sum on poverty relief measures.
The measures are to be approved by parliament by mid-May, with the governmen hoping to reach an overall deal at a May 22 meeting of eurozone finance ministers.
A compromise is required to unblock a tranche of loans Greece needs for debt repayments of seven billion euros in July.
A government source early Monday said Athens and the creditors were inching towards a preliminary agreement.
"There are four dossiers with important issues, and four or five dossiers with lesser issues (remaining)," the official said, according to state agency ANA.
In an interview Sunday, German Finance Minister Wolfgang Schaeuble said a May 22 deal was feasible "if the (Greek) government respects all the agreements."
"Greece has made progress, the last figures are positive. But the government has not yet fulfilled all the agreements," he said.
Greece and its creditors agreed a third, 86-billion-euro ($94-billion) bailout deal in July 2015.
But the IMF has so far refused to take part after two prior programmes on the grounds that the targets were unrealistic and Athens' debt mountain unsustainable.
Additional debt relief for Greece has proved a contentious point for many of its European creditors including Germany, where additional concessions are unpopular with a general election looming in September.