The author of a Khmer Rouge memoir who now lives in the US is raising funds to help education in Cambodia.
Hun Sen said the courts had made an independent decision free of political influence.
Duch, whose real name is Kaing Kek Iev, faces the prospect of release at the age of 86.
Following last week's verdict of Duch, 24 of 90 victims who claimed they lost loved ones in his torture center were dismissed.
Following Duch’s verdict and sentencing, issued Monday, the EU immediately announced a contribution of $2.6 million to the tribunal.
Duch was the first to be tried under the new court, which formed in 2006 after years of wrangling between the government and the UN.
Victims of the Khmer Rouge say they should be granted more compensation than was handed over by the Khmer Rouge tribunal on Monday.
During his 77-day proceedings, Duch admitted to heading Toul Sleng, a top secret detention centre for the worst "enemies" of the state.
The 93-minute film has won 16 awards in the US and other foreign countries, including the Special Jury Prize at Sundance.
The UN-backed court is expected to release the verdict on July 26, following court proceedings that began in March 2009.
A trial is expected in March 2011.
Observers say the tribunal risks losing its legitimacy if its objectivity is compromised by politics.