With the help of organized criminal elements, Islamic State terrorists reportedly are buying legitimate British passports that can evade security detection from security authorities, the Daily Beast reports.

An Italian intelligence investigation into the Camorra mafia discovered an advertisement on the deep web that linked to a Naples firm capable of producing sophisticated biometric passports.

"We are selling original UK Passports made with your info/picture. Also, your info will get entered into the official passport database," the advertisement reads. "So its (sic) possible to travel with our passports. How do we do it? Trade secret! Information on how to send us your info and picture will be given after purchase! You can even enter the UK/EU with our passports, we can just add a stamp for the country you are in."

Other investigations also shed light onto the broader ties between terrorists and European criminal organizations, including in the smuggling of weapons and forged documents.

Last year Italian authorities arrested an Iraqi man in Naples for facilitating weapons and document transfers to the Islamic State.

"Naples has been, for many years, a central logistics base for the Middle East," prosecutor Franco Roberti told the Daily Beast last year, adding that "the Camorra (mafia) is also active in the world of jihadist terrorism that passes through Naples."

Terrorists are diversifying their funding sources through various criminal means to underwrite their violent and nefarious activities. The criminal-terrorism nexus manifests itself in several ways: mainly in the form of cooperation between terrorist groups and organized criminal elements, and crimes by terrorists which are conducted to finance their own operations. Terrorists' reliance in counterfeiting in particular has attracted more attention recently with the rise of Islamic State networks in Europe and other parts of the world.

Lacking a formal state sponsor, and facing setbacks in Syria and Iraq, the Islamic State may start to depend more on criminal relationships to fuel their operations and to infiltrate terrorists into Western for the purposes of carrying out attacks abroad.