Thousands of Polish union members marched in Warsaw on Wednesday, burning tires and beating drums in anger over the government's labour and pension policies.
The protesters -- who numbered 15,000 according to the municipality and 23,000 according to organisers -- called on the government of Prime Minister Donald Tusk to resign at the start of the four-day demonstration.
Carrying the flags of Solidarity and other trade unions, they gathered around noon (1000 GMT) in front of the main ministries before marching towards parliament to the sound of drums, whistles and sirens.
They called for a lower retirement age, which the government has raised to 67, and a higher minimum wage.
They also denounced low job security in the EU member and accused Tusk, whose term is up in 2015, of ignoring their demands and refusing to engage in dialogue.
"I want an end to temporary contracts," said Zdzislaw Urabanek, a chemical plant worker from the eastern town of Pulawy.
"Young people are only getting contracts for one, two, three months," the 60-year-old Solidarity member told AFP.
"Not a fan of this government," said Benedykt Moczala, a 51-year-old miner from the southern Silesia coal basin, to which his friend added: "They're all thieves."
Organisers said some 600 demonstrators set up tents in front of parliament, where they will spend the night through Saturday, when the unions expect 100,000 people.
Myanmar opposition leader Aung San Suu Kyi, in town for the start of her European tour, said she had to brave the rain to walk over to parliament after unionists blocked traffic.
"I was very interested to find democracy in action just in front of the hotel," she told reporters before meeting with Polish parliamentary speaker Ewa Kopacz.
"I think part of democracy is to be able to demonstrate your feelings, yearnings and ask for what you want in a peaceful way as the people in front of the parliament did.