By Jon Herskovitz

JOHANNESBURG (Reuters) - Dirk Coetzee, who led an apartheid-era death squad and later sought protection from the resistance movement that brought down South Africa's white minority government, has died, a hospital said on Thursday.

Coetzee, 57, was a former police captain who blew the lid on his hit squad and fled the country in 1989, unleashing revelations that deepened the global isolation of the apartheid regime.

The commander of the covert police assassination unit based at Vlakplaas, a farm outside the capital Pretoria and a training base for hitmen targeting anti-apartheid leaders, eventually landed in London after exposing the group in an interview with a liberal Afrikaans newspaper.

Coetzee claimed responsibility for several killings of African National Congress (ANC) members. His group recruited among the ranks of blacks who left the liberation movement and turned them into killers.

But once he was in exile, he joined the ANC, became known as "Comrade Dirk" and turned to the group led by the likes of Nelson Mandela and O.R. Tambo for protection.

"They were the only people who could check my story and see if I was speaking the truth," he told Reuters in 1990. "For me, it was a hell of a risk to come over to the ANC," he said.

The decision to leave South Africa was not entirely an attempt to clear his conscience.

Coetzee, whose police career was in jeopardy just before he left, was also named by one of his hitmen as a co-conspirator in the killing of Durban human rights attorney Griffiths Mxenge in 1981.

Coetzee proved to be a treasure chest for the ANC, shedding a light on the brutality and dirty tricks the apartheid government used to stay in power. He became an assassination target for the white-minority government.

Coetzee later returned to South Africa and became a member of the post-apartheid spy service under then President Mandela.

In 1997, he was granted amnesty by the government's Truth and Reconciliation Commission for the killing of Mxenge, who was stabbed 45 times.

The National Prosecuting Authority had been working with Coetzee to help find the body of ANC activist Sizwe Kondile, who was killed by his group.

In dramatic testimony to the Truth and Reconciliation Commision, Coetzee talked about how his band of assassins started barbecuing meat for a meal after separately setting the corpse of Kondile on fire.

Coetzee, died at Life Wilgers Hospital in Pretoria from kidney failure, a hospital spokeswoman said.

(Reporting by Jon Herskovitz; Additional reporting by Marius Bosch; Editing by Jason Webb)