Family members say Cambodia's Vann Nath, one of only seven survivors of a vast and notorious Khmer Rouge torture center, is in a coma and near death at a Cambodian hospital.

The 66-year-old human rights icon and artist survived the infamous Tuol Sleng prison, where more than 12,000 people died in the 1970s under Khmer Rouge rule. He was hospitalized Friday with an apparent heart attack, and a senior hospital official in Phnom Penh said Tuesday there is little hope for his survival.

News of Vann Nath's illness comes as an international tribunal prepares to begin the long-awaited trial of the four most senior surviving Khmer Rouge leaders — all charged with atrocities during the group's 1975-1979 rule. The defendants, including the nominal Khmer Rouge head of state, 79-year-old Khieu Samphan, face charges of religious persecution, torture and genocide in the deaths of as many as 2 million people.

Vann Nath's health crisis also comes as the tribunal deliberates a verdict for war crimes suspect Duch, the one-time chief of Tuol Sleng prison. Duch was convicted of war crimes and imprisoned earlier this year for 30 years — a sentence later reduced to 19 years because of time served in detention. He has appealed his conviction.

Vann Nath is widely seen as a leading advocate for victims of Khmer Rouge atrocities. His 1998 memoir — A Cambodian Prison Portrait: One Year in the Khmer Rouge's S-21 Prison — is the only written account by a survivor of the prison. The book has been translated from English into French and Swedish.