MADRID - An Austrian doctor accused of killing hundreds of inmates at a Nazi concentration camp during World War II has been hiding in Spain for the last 20 years, a Spanish newspaper reported yesterday. German authorities have said they are hunting for Aribert Heim, 91, known as "Doctor Death."

Heim worked in Mauthausen concentration camp in Austria and killed hundreds of inmates by lethal injection and torture, according to the Nazi-hunting Simon Wiesenthal Center, which had suspected Heim was in Spain.

Spain's El Mundo newspaper reported that Heim moved to Spain in 1985, and had been sheltered by Odessa, a secret group believed to have helped Nazi war criminals. "Odessa, which has had one of its main operating bases in Spain, has kept Doctor Aribert Heim ... hidden in our country for the last 20 years," it said.

The report quoted investigators as saying Heim had lived on the Costa Brava: "Police suspect that, knowing that he had been located, Heim left the area to go to the Marbella area."

Some of Heim's victims were Spaniards. Many Republicans who fled to France after their defeat in the 1936-39 Spanish civil war were sent to Mauthausen after being handed over to the Nazis. Some 5,000 Spaniards died there.

According to El Mundo, Heim was in Mauthausen from October 8 to November 29, 1941, and was involved in injecting prisoners with poison and in doing unnecessary operations.