Yoo Young-Chul

Police were hunting for more bodies on Monday after an alleged South Korean serial killer said he had murdered more than 20 people.

Yoo Young-Chul (33) targeted sex workers and the elderly in a killing spree that dates back to last September and has stunned South Koreans, police said.

"This is the worst serial killing in the history of Korea," police inspector Huh Won-Sik told AFP.

Yoo was arrested on Sunday after admitting 19 killings. Following further interrogation, Yoo claimed he had murdered 26, police said as they accompanied the convicted rapist on a hunt for more bodies in Incheon, a port city 40 kilometers west of Seoul.

The alleged serial killer has also told police he killed, dismembered and buried more bodies in the southern port city of Busan.

Yoo preyed on women employed in the sex trade and vulnerable old people, police said.

On Sunday the dismembered remains of 11 women were recovered from shallow graves in the hills around Seoul, where Yoo lived. Most of the victims were prostitutes working in massage parlours or as bar hostesses, police said.

They said they could not corroborate Yoo's claim that he had killed 26 people but said the number of victims was expected to exceed 20.

Yoo killed and dismembered his victims in brutal fashion, using an electric saw, knives, hammers, axes and scissors. South Korean TV stations showed chilling footage of bloody crime scenes.

"He took off fingerprints from the female victims after chopping their bodies up at his house," senior investigator Kang Dae-Won told reporters on Sunday.

South Korean police chief Huh Jun-Yong said earlier that Yoo had a history of mental problems and was a convicted rapist who had spent several years in prison.

After his wife divorced him in 2002, he was driven to kill by a hatred of women and the wealthy, police said.