Police in Democratic Republic of Congo on Tuesday carried out arrests among opposition campaigners as they sought to rally, including a leader who had received a prominent US award, the group said.
Ten people were arrested in the eastern city of Goma, the Struggle for Change (Lucha) group said on Twitter, while Lucha member Ghislain Muhiwa said "a total of 27 people" had been detained.
Those arrested included Rebecca Kavugho, 23, who received an International Woman of Courage award from the US State Department last year, Muhiwa said.
A police commander, speaking to AFP on condition of anonymity, said "about 20 people" had been arrested for "disturbing public order."
"They will be questioned and then prosecuted," he said.
Lucha, a non-violent group whose stronghold is Goma, is prominent in the campaign against President Joseph Kabila, who is facing a wave of protest against his rule.
Kabila, in power since 2001, refused to leave office when his term expired in December 2016.
Elections, twice delayed, are due to be held on December 23, but opposition groups say they have little hope that the vote will be fair and credible.
Public rallies have been banned since September 2016, when dozens of demonstrators were killed.
Last year, at least 47 people were killed, according to a UN report seen by AFP last month.
In a major exception, opposition supporters were allowed to stage a rally on April 24 in Kinshasa, the Democratic Republic of Congo's capital.
In the east of the vast country, however, police are still breaking up demonstrations and carrying out arrests, campaigners said.
The UN, along with the United States, Britain, France and the European Union, has repeatedly warned the government about repression, and also urged the opposition to protest peacefully.
In addition to a deep political crisis, the DRC is struggling with armed conflict in its vast, lawless east, which is under the sway of multiple rebel groups.
Lucha said it wanted to demonstrate on Tuesday - the sixth anniversary of its founding - to help draw attention to "massacres" by militias in the Beni region north of Goma.
However, the city mayor, Thimotee Muissa Kenseis, said that the authorities had banned all rallies after a shootout in a district on the outskirts of Goma on Sunday in which seven people died and 18 were injured.