Kean Wong:
Around 5,000 people gathered just outside Phnom Penh today. They were there to remember those who died during the reign of terror of Pol Pot and his Khmer Rouge regime. Here's more from Chheung EK.

Chheung Ek was one of the infamous 'killing fields' in Cambodia. 1.7 million people are thought to have perished here between 1975 and 1979.

Students from the Royal University of Fine Arts re-enacted killing scenes as monks took in food offerings from relatives of those who died.

[Sok Chayhong, Khmer Rouge Survivor]:
"I'm offering food to my relatives and also to whoever died during the Pol Pot regime. If they don't have relatives to do this for them, I am alive so I can offer food to them."

Vietnam invaded Cambodia at the end of 1978, bringing an end to the murderous regime.

Now every year on May the 20th, Cambodia commemorates this painful past. A "Day of Hatred" when people are allowed to vent their anger... to remember and not to allow such killings to happen again.

[Kep Chutema, Mayor, Phnom Penh]:
"We remind the younger generation to remember the killing that our Khmer people suffered and we ask not to allow this regime to happen over again—not in this country nor anywhere else in the world."

Khmer Rouge leader Pol Pot, died in 1998, but another four former leaders of the regime are being charged in a U.N-backed court for the crimes.

But survivors of the genocide want a faster tribunal process for justice to be served.