US and Belgian flags have been burned by protesters – who also set alight tyres as they targeted Western embassies in the capital of the Democratic Republic of Congo (DRC).
Police fired tear gas to disperse the crowds in central Kinshasa on Monday.
The demonstrators were angry at what they saw as Western support for neighbouring Rwanda after it was accused of backing a rebellion in the east of the DRC.
Rwanda has denied the claims, which came as the Tutsi-led rebel group M23 advanced and threatened the strategic city of Goma.
But the DRC, Western governments including the US and Belgium, and a UN expert group say M23 benefits from Rwandan support.
The armed rebels in the east of the country have committed unlawful killings, rape, and other apparent war crimes since late 2022, according to Human Rights Watch.
On Monday, protesters gathered at the US and French embassies, and the offices of the UN mission, despite security being increased after UN staff and vehicles were attacked on Saturday.
Some people threw stones and tried to break CCTV cameras at one of the US embassy offices, while others chanted: “Leave our country, we don’t want your hypocrisy”.
“The international community remains silent while Congolese are being killed; they finance Rwanda,” said motorcyclist Fabrice Malumba, who took part in the demonstration in front of the US embassy.
“The Westerners are behind the looting of our country, Rwanda doesn’t work alone, so they must leave our country,” said Pepin Mbindu, who also joined the protest.
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Elsewhere, a demonstrator reportedly removed an EU flag from the entrance of a large hotel in the city centre.
The DRC’s vice prime minister and minister of foreign affairs Christophe Lutundula has met ambassadors and heads of diplomatic missions in Kinshasa, and later said security measures would be taken to protect their buildings.
Decades of conflicts in the eastern DRC between rival armed groups over land and resources, and attacks on civilians, have killed hundreds of thousands of people and displaced more than seven million.