Tens of thousands of people have taken to the streets in Brazil to demonstrate against the government.
Organisers said 50,000 people - a record number - turned out in Sao Paulo alone for a seventh day of protests against the new President Michel Temer.
Mr Temer took office after Dilma Rousseff was removed from the presidency in an impeachment trial.
The rally began peacefully but police used tear gas, stun grenades and water cannon as clashes broke out at the end.
They said they had been forced to take the measures to avoid vandalism.
Several people were reportedly injured including a BBC journalist.
Some protesters responded by throwing bottles and stones at riot police, and building and setting fire to barricades.
Mr Temer said the protests were "small groups, not popular movements of any size".
While at a G20 summit in China, he told reporters: "in a population of 204 million Brazilians, they are not representative."
I was beaten up by police - Felipe Souza, BBC Brasil:
A group of riot police suddenly decided to change course. I leaned against the wall to wait for them to pass.
I was wearing a BBC Brazil vest and badge and I raised my hands and said I was press.
"Move over!" said at least four police just before catching me with truncheon blows on the right forearm, left hand, right shoulder, chest and right leg.
My forearm swelled up and turned purple. The phone I was using fell to the ground and the screen was broken. Luckily, the blow I took to the chest was cushioned by the vest I was wearing. I also wore a helmet and gas mask - complying with internal BBC rules for covering demonstrations.
The Secretariat of Public Security of Sao Paulo said that "the facts narrated by the reporter will be investigated and the journalist should file a police report".
Brazil's Senate voted to remove Dilma Rousseff from office last week, for manipulating government accounts to hide a shortfall in the government's budget.
It put an end to the 13 years in power of her left-wing Workers' Party. Ms Rousseff had denied the charges.
Mr Temer was the vice-president under Ms Rousseff and under her predecessor Luiz Inacio Lula da Silva (known as Lula). He became the acting president while Ms Rousseff was suspended before her impeachment trial, and was sworn in as president at the end of August. He will serve the rest of what would have been her second term, which ends in 2019.
Many protesters called for immediate elections. In Sao Paulo, Gustavo Amigo said: "We're here to show that the people still have power and that despite the coup, we are here in the street to bring down the government and call for a new election."
Ms Rousseff and her supporters have consistently called her impeachment a coup.
The Paralympic Games will begin in Rio de Janeiro on Wednesday.