The government has sent a request to Unesco to include the Tuol Sleng torture museum on a list of protected sites to preserve thousands of documents and photographs remaining from the period of the Khmer Rouge.

"We sent the documents to Paris Friday, Aug. 29, in order for [Unesco] to consider admitting Tuol Sleng as a Memory of the World site," Yos Eang, deputy secretary-general of the national commission for Unesco, said. "But they have not recognized it yet. And then we have to wait [to see] if they have questions to ask, and if we have some other elements to add."

The application included a request to protect the photography, printed documents and building of Tuol Sleng and the Choeung Ek "killing fields" on the outskirts of Phnom Penh, he said.

"The aim is that they will protect our documents with [international] standards for the sake of the research of Cambodian and international people," Yos Eang said.

There were at least 15,000 prisoners detained at Tuol Sleng between 1975 and 1979, and around 4,000 confessions were preserved at the site, according to a statement issued by the Phnom Penh office of Unesco Aug. 29.

More than 6,000 prisoner biographies, 6,000 photographs and negatives of prisoners, as well as photos of visitors from China, are also kept at the site, the Unesco statement said.

Some documents have already been used for proceedings at the Khmer Rouge tribunal, the statement said.

The former Phnom   Penh high school was made into a prison under the Khmer Rouge and was then turned into a museum following the occupation of the Vietnamese in 1979.

"This is a historical event that will make the world remember the crimes committed against our Cambodian people," said Khun Samen, deputy secretary-general of the Ministry of Culture, who is in charge of museums.