It is claimed the woman was taken to an abandoned office block on July 11 close to Milan's Central station in the boot of a vehicle.
A spokeswoman for the Foreign Office said: "We have been providing consular support to a British woman in Italy and are in touch with local authorities".
During her detention, Herba had demanded the model's agent pay $300,000 to avoid the model being sold online though no ransom appears to have been paid, police added.
After the 20-year-old arrived, she was drugged, stuffed in a bag and loaded into the back of a auto and driven to a farmhouse near Turin around 120 miles.
Authorities said the kidnappers were going to release her "because she had a 2-year-old child" and their "rules exclude kidnapping mothers".
She is believed to have been drugged and transported in a bag to a secluded village near Turin, before being released on July 17.
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The woman was then kept handcuffed to a wooden chest of drawers in a bedroom for six days until she was released.
"Analysis of his email shows this man belonged to an organisation called "Black Death", Milan prosecutor Paolo Storari said in a media conference overnight, The Telegraph Reported.
The unnamed suspect faced pre-trial before magistrate Anna Magelli yesterday.
The 20-year-old woman, who has not been named, was allegedly kidnapped by two men on 11 July as she turned up for a fake photo shoot.
Officers went through Herba's phone and computer and said they found photos of the woman and material stating she was for sale, while hair from both the model and Herba was found in the boot of his auto.
The agent then contacted police and Herba reportedly negotiated a £50,000 ransom with them which he expected to receive at the Consulate.
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