About 300 Latvians marched through the capital on Monday to commemorate countrymen who fought in a Waffen SS unit during World War II, defying a ban by city officials.
Dozens of protesters - mainly ethnic Russians - jeered at the participants as they carried flowers to the base of the Freedom Monument in downtown Riga. Fearing clashes, police had set up barricades to keep the two sides apart at the annual event.
No violence was reported, though police spokeswoman Ieva Reksna authorities said four people were detained for unruly behavior.
Unlike previous years, Riga city officials had prohibited World War II veterans and patriotic organizations from holding demonstrations, fearing they would increase tensions in the crisis-hit Baltic nation. Two months ago, anti-government protesters clashed with police outside Parliament in Latvia's worst riots since it regained independence from the Soviet Union in 1991.