Several thousand people rallied Wednesday in the eastern DR Congo city of Goma to protest against Rwanda, a day after the government reiterated claims Kigali backed a notorious rebel group.
Tension in the border city was high as riot police dispersed some demonstrators, many of them angry young men stripped to the waist, who tried to push through the frontier post with Rwanda, an AFP reporter saw.
At least one person was injured.
The crowd chanted slogans against Rwanda and its president Paul Kagame.
"No more Rwandans, let's go and sort out Kagame," was one.
"We are demonstrating against the M23's incursion in the Democratic Republic of Congo.
"We are calling on the government to give us uniforms and weapons so that we can fight" the Rwandan army, a demonstrator who gave his name as Eric told AFP, to the applause of other demonstrators.
Banks, petrol stations, schools, shops and other outlets were closed across Goma, and only a few pharmacies appeared to be open.
Friction between the Democratic Republic of Congo (DRC) and its eastern neighbour has surged in the past few weeks over the M23 rebel group.
A primarily Congolese Tutsi militia that is one of scores of armed groups in eastern DRC, the M23 leapt to global prominence in 2012 when it captured Goma.
It was forced out shortly afterwards in a joint offensive by UN troops and the Congolese army.
The rebels resumed fighting last November after accusing the Kinshasa government of failing to respect a 2009 agreement under which the army was to incorporate its fighters.
Clashes intensified in March, causing thousands of people to flee, and on Monday the rebels took the trading town of Bunagana.
The DRC has accused Rwanda of backing the rebels -- an assertion that it repeated on Tuesday after several hundred people rallied in Kinshasa to demand President Felix Tshisekedi break off diplomatic ties with Kigali.
Rwanda denies the allegation of involvement. Both sides have accused each other of cross-border shelling.
Relations between Kinshasa and Kigali have been strained since the mass arrival in DRC of Rwandan Hutus accused of slaughtering Tutsis during the 1994 Rwanda genocide.