Chloe Ayling says she was held captive in a remote Italian farmhouse for six days

But Herba also emailed The Daily Mirror two days into the kidnapping, under the heading ‘British model kidnapped by Russian mafia’, apparently offering to sell the story as well as photos of Ms Ayling.

He told the Italian police that he had falsely claimed the Russian mafia were involved in order to “attract attention”.

The attempt to sell the story – which could well have compromised any effort to traffick the young model – emerged during questioning of Ms Ayling and her alleged kidnapper by police in Milan.

Asked if she knew that Herba had tried to contact the newspaper, she said: “I know nothing about that at all.”

It comes as it emerged that the Black Death group were investigated in 2016 amid fears that they were selling a 15-year-old British girl in an online auction.

Lukasz Pawel Herba, a Polish citizen with British residency, pictured after his arrest credit: ANSA/ITALIAN POLICE PRESS OFFICE

Europol had monitored the group's Dark Web site of as they advertised two teenagers for auction, one of whom was under the age of consent and described as "pure".

The auction of the 15-year-old, whose name was given as Laura, started at $750,000 and was due to take place at the end of May 2016, with the Black Death website warning that it was "fully booked".

A second auction for a 17-year-old girl born in the UK named only as Gemma had been scheduled to take place just days earlier with a starting bid of $120,000.

The age, hair colour and measurements of both teenagers were posted alongside their auction adverts.

It is unclear whether the girls were real or the auctions went ahead, but a version of the Black Death's website saved by the European Cybercrime Centre has emerged as part of the investigation into the kidnap of Miss Ayling.

A Europol spokesman said: "An EU Member State previously requested cross checking of Europol databases on this group and an answer was provided.Since this answer contained classified information, Europol cannot disseminate it outside the law enforcement community."

Italian Police handout shows a screenshot of a "Black Death Group" document on a laptop belonging to Lukasz Pawel Herba credit: Reuters

It came as Miss Ayling's agent revealed she was forced by Italian police to stay in the country for for almost three weeks after her release.

Phil Green, of Supermodels Agency, said: "Chloe had her passport detained by Italian police who would not let her return to the UK until she gave evidence at a pre-trial hearing on August 4."

"Today she is debriefing Met Police and the Foreign Office, and has requested to spend the rest of the day in privacy with her mother," he added.

The transcript of the questioning of Miss Ayling shows that Italian police asked her why she had agreed to go shopping for shoes with Herba the day before she was released.

The two of them were recognised by the owner of a shoe shop in the town of Viu’ in the Piedmont region of northern Italy.

Chloe Ayling has returned to the UK where she has been debriefed by British police

Pressed on why she had not revealed the shopping trip to police before, she began to cry.

“Is it not strange that you went to buy shoes with your abductor?” a detective asked her.

She said she went along on the shopping trip because by that time Herba had promised to set her free, after apparently taking pity on her when he discovered that she had a young child.

The police also asked her whether she had had sex with her captor, after they found traces of sperm on a bed in the farmhouse where she was held.

She categorically denied that they had had sexual intercourse.

“He slept in the other room but after the second night he took the cuffs off my feet while reassuring that me sooner or later I would be freed, so I should not risk fleeing or my life would be at risk,” she told police.

“From that time I slept in his room sharing his double bed. He never sexually molested me or requested sexual relations. The ‘Black Death’ organization prohibits it and severely punishes its members who touch kidnapped girls destined for sale at auction.”

She said she was given underwear and a clean T-shirt every day.

The house where Chloe Ayling tells police she was held credit: Italian Police

She told them: “He tried to make sexual advances but I always rejected them, promising him a more intimate relationship in the future. I made him believe we could be more intimate when the whole thing ended.”

The police also quizzed the model, from Coulsdon in Surrey, about why Herba had chosen to give her back her freedom by personally taking her to the British consulate in Milan on July 17 – a decision which resulted in his arrest.

She said her abductor had initially planned to drop her off a 15-minute walk away from the consulate but that he changed her mind.

When they arrived at the consulate early in the morning it was closed, so they went to a nearby café for breakfast.

Police have described Herba, who is in custody, as a “mythomaniac” and a “pathological liar”.

Under questioning by Italian police, he claimed he became part of the kidnapping gang because he was suffering from leukemia and desperately needed to raise half a million pounds for treatment.

He could provide no medical proof of having the illness.

The Daily Mirror said in a statement that they had received the message about Miss Ayling that was also sent the the Sun and someone from C4's Dispatches, but " there was nothing in the email to suggest it was from the alleged kidnappers, nor was it an attempt to sell a story about a kidnap.

"We contacted the modelling agency copied into the email, but our call was not returned. No further emails were received."