Human rights activists say the protester died by a gunshot to the head during a street battle with police, according to a Voice of America report.
The demonstrations began peacefully Sunday as 20,000 people gathered in Freedom Park for a rally led by opposition leader Sam Rainsy.
But when protesters moved to other parts of the city and attempted to remove barricades set up by police, clashes began and the police started firing tear gas, smoke grenades and water cannon at the crowds.
Chan Soveth of Cambodian Human Rights and Development Association (ADHOC) told Voice of America,”There was a clash that caused people to be injured and killed but we did not know how many were killed. We know that a young man died and we took a photo. Another injured person was shot in his stomach because armed authorities used guns to shoot, and many were arrested,” he said.
The French news agency quoted military police spokesman Kheng Tito who denied that police used live rounds against the demonstrators. Another violent clash occurred at a police barricade near the Royal Palace in which several protesters were injured.
The protesters are demanding an independent investigation of the election in which official results declared Prime Minister Hun Sen the winner, though with a reduced parliamentary majority. The opposition alleges widespread election fraud.
Hundreds of protesters camped in Freedom Park into the night Sunday, vowing to remain there for several days.
Prime Minister Hun Sen and opposition leader Sam Rainsy were due to meet again Monday to continue talks aimed at resolving the crisis.
Cambodian King Norodom Sihamoni had brought the two rivals together Saturday for a rare meeting, but it ended without a breakthrough. Image/AFP