Hundreds of people gatheredin central Athens to protest against plans to increase Sunday trading hours in a rally organised by unions and communist groups.
Sunday's demonstration largely drew members of the PAME communist labour union alongside others representing small- and medium-sized businesses (SMEs) who oppose reforms demanded by Greece's international creditors.
Demonstrators rallied in the city centre carrying flags and banners in Greek reading "Never work on Sunday," an AFP correspondent said.
Shops in Greece are currently compelled to open on the first Sunday of every month in a step imposed three years ago by the country's creditors.
The reform would increase the number of Sundays from 12 times a year to 30.
Extending Sunday trading is one of a list of demands by the creditors, the European Union and the International Monetary Fund, which are among the measures that must be approved by the Greek parliament by mid-May.
Unions have called a 24-hour general strike on May 17 to protest against the new measures, whose adoption is a prerequisite for unblocking a new seven-million-euro ($7.7 million) tranche of loans that Athens needs to meet its debt repayment schedule in July.
Deregulation has been at the heart of the "reforms" demanded by Greece's creditors since the explosion of the country's debt crisis in 2010, with the aim of boosting growth.
Following an unprecedented six-year recession, the Greek economy is still struggling to recover with growth flat in 2016.
For 2017, the European Commission has revised down its growth projections for Greece, from 2.7 percent to 2.0 percent.