Phnom Penh - Thousands of photos and documents from the Khmer Rouge S-21 torture center, also known as Toul Sleng, have been submitted for recognition on the UNESCO international register, the UN cultural body said in a press release received Thursday.

The Tuol Sleng Genocide Museum archives in the capital were registered by UNESCO's Memory of the World grouping for Asia and the Pacific region in February and are now being submitted for listing on the UNESCO international register, the body said.

The detailed S-21 archives document the fate of the more than 15,000 prisoners held in the Khmer Rouge's deadly 1975-1979 Democratic Kampuchea regime, during which up to 2 million Cambodians perished.

Only 14 survivors were originally identified, but researchers last week revealed newly available documents showing 177 prisoners were released prior to 1978.

Hundreds of thousands of Cambodians died as victims of the killing fields from torture, disease, starvation, overwork and executions across the country, but S-21 remains unique for its harrowing and painstaking documentation of Khmer Rouge atrocities.

S-21 documents include 4,186 confessions, 6,226 prisoner biographies, 6,147 photos, demolished buildings, research activities, mass graves and remains of victims.

"All documents and items that are providing an essential part of the evidence advanced during the pre-trials and trials of the senior leaders of the Democratic Kampuchea for serious crimes under national and international law," UNESCO said in the release.

The Memory of the World programme guarantees regional recognition and promotes preservation, digitalization, and public access to member sites and documents, according to UNESCO. (dpa)