Local resident shows the dungeon where criminal happened to reporters.

A Chinese man has been arrested on suspicion of killing two nightclub hostesses and keeping another four women as sex slaves in a basement dungeon, according to police.

Reports said that Li Hao, a 34-year-old former firefighter who is married and has a son, allegedly held the women for years in a 20-square-metre (215-square-foot) underground prison he built in central China's Luoyang city.

The Southern Metropolis Daily said he had confessed to buying the basement four years ago and spending nights digging the prison four meters (13 feet) under the basement, where he spent two weeks a month with his captives.

Li had told his wife he had a night job as a guard, the paper said. He was caught earlier this month when one of his captives escaped and went to the police.

"Li has been arrested and brought to justice," a police officer in Luoyang told AFP by telephone.

"We are still on the case and investigations continue," added the officer, who declined to give his name.

The Global Times English-language daily quoted local resident Tian Yichen as saying that the case had "shocked the whole city".

"The building is in the downtown area, and only three kilometers (1.8 miles) away from the Luoyang public security bureau."

A preliminary investigation reportedly showed that the two bodies the police found in the dungeon on September 6 had been killed within the last year.

Journalist Ji Xugang of the Southern Metropolis Daily, the first newspaper to report the case, told the Global Times he was interrogated by local police over his story.

"They believed that the report tarnished their image. But this is a typical crime. The public needs to know the truth," he said.

The case is the second sex slave scandal to hit China since February, when a 40-year-old man was sentenced to death for kidnapping, beating and raping two teenage girls in an underground cell in Wuhan, the capital of central China's Hubei province.

Though the court stated Zeng had "exerted an extremely negative influence on society," he later won an appeal and his death sentence was stayed in July, state media reported. It is unclear what has happened to him since then.

The cases recall a number of horrific cases in other countries that have horrified the world in recent years.

Austrian Josef Fritzl, who held his daughter Elisabeth as a sex slave in a cramped windowless dungeon for 24 years and fathered seven children with her, was jailed for life on rape and murder charges in March 2009.

Also in Austria, Natascha Kampusch was kidnapped at the age of 10 and held captive in a tiny cellar for eight and a half years until she escaped in August 2006.