By Guy De Launey
BBC News, Phnom Penh
Cambodian Prime Minister Hun Sen has turned down calls for the remains of thousands of victims of the Khmer Rouge to be cremated.
Many in Buddhist Cambodia are uncomfortable with the display
He said it was important for the skulls to stay on display as evidence that millions died during the late 1970s.
One memorial stupa, at Choeung Ek, has become the best-known site of the so-called Killing Fields.
The trials of the surviving former leaders of the Khmer Rouge are due to start later this year.
Memorials like the glass-sided structure at Choeung Ek's genocide museum have become a focus of controversy.
Once they were quiet if grim reminders of what happened under Pol Pot's murderous regime, but now they have become tourist attractions.
More than 100,000 people visited Choeung Ek alone last year.
This has caused discomfort in a Buddhist country which largely believes that a body has to be cremated for its soul to escape.
But the prime minister says those concerns are outweighed by the need to make sure that no-one can deny what happened three decades ago.
Hun Sen's remarks come with the long-awaited Khmer Rouge trials still bogged down in disputes between local and international legal officials.
Meetings next month will attempt to resolve the difficulties involved in making sure that the special courts provide an international standard of justice within the Cambodian system.