A police officer displays two bottles containing human fat while another officer holds seized sticks of dynamite during a press conference in Lima. (Karel Navarro/Associated Press)

Three members of a Peruvian gang have confessed to killing people and draining the fat from the corpses to sell on the black market for use in cosmetics, according to police officials.

Col. Jorge Mejia, the chief of Peru's anti-kidnapping police, said at a news conference on Thursday that two of the suspects were arrested carrying bottles of liquid fat and told police it was worth $16,000 a litre.

Medical experts, however, expressed skepticism that a major market exists for fat, saying that while human fat can be used in anti-wrinkle treatments, it is always extracted from the patient being treated.

Mejia said the fat was allegedly sold to intermediaries in Peru's capital, Lima, and police suspect it was then sold to cosmetic companies in Europe, but he could not confirm any sales.

Three suspects confessed to killing five people, but the gang may have been involved in dozens more, police said. This year alone, at least 60 people are listed as missing in Huanuco province, where the gang allegedly operated, but the province is also home to drug-trafficking leftist rebels, police said.

Doubts about black market for fat

Six members of the gang remain at large, including the band's alleged leader, Hilario Cudena, 56, who one of the suspects told police had been killing people for human fat for over three decades.

The remains of some of the victims were found at a rural home in Huanuco, according to police video.

Medical experts were doubtful the trade of human fat would be lucrative.

Dr. Neil Sadick, a professor of dermatology at Cornell Weill Medical College in New York, said using a product with someone else's fat carries the risk of an immunological reaction, which is why people who do use products with human fat get the fat from their own body.

Dr. Adam Katz, a professor of plastic surgery at the University of Virginia medical school, said he was baffled that there would be a black market at all for fat.

"It doesn't make any sense at all, because in most countries we can get fat so readily and in such amounts from people who are willing and ready to donate that I don't see why there would ever be a black market for fat, of all tissues," he said.

With files from The Associated Press