According to documents published by WikiLeaks the US Central Intelligence Agency has issued advice for its agents on how to infiltrate international passport control systems, including in the European Union and the Schengen area.

MOSCOW, December 22 (Sputnik) — The US Central Intelligence Agency has issued advice for its agents on how to infiltrate international passport control systems, including in the European Union and the Schengen area, according to two previously undisclosed documents published by WikiLeaks on Sunday.

“The European Union’s Schengen biometric-based border-management systems pose a minimal identity threat to US operational travellers because their primary focus is illegal immigration and criminal activities, not counter-intelligence,” reads one of the documents, dated January 2012.

The CIA advice booklet, entitled “Schengen Overview”, gives detailed information on customs procedures in Europe and threats they pose to agents using false documents. While biometric systems are currently not used for people with US documents, this could possibly change in 2015, increasing the “identity threat level”, according to the CIA.

The second document, dated September 21, 2011, gives advice on how to pass airports screenings across the world.

The manual, titled "Surviving Secondary", notes that airport watch lists may include names of confirmed or suspected intelligence agents and lists a number of signs that could disclose one’s identity, such as apparent nervousness and inability to speak the language of the passport-issuing country.

The document also lists special security procedures in a number of international airports and underlines that a “consistent, well-rehearsed, and plausible cover is important for avoiding secondary selection and critical for surviving it.”

According to the manual, accounts on Twitter and LinkedIn could help make the false identity more plausible.

In a highlighted box entitled “The Importance of Maintaining Cover––No Matter What”, the CIA describes a situation where an intelligence officer was selected for secondary screening in a EU country, possibly due to “overly casual dress inconsistent with being a diplomatic-passport”.

When the CIA officer’s bag screened positive for traces of explosives, he presented a cover story on having engaged in counter-terrorism training in Washington DC. Even though local security officials initially concluded that the agent had trained in a terrorist camp, he “consistently maintained” his cover story and was eventually allowed to proceed with his travels.

The publication of the two travel advice documents is the second release within the WikilLeak's so-called CIA Series, which is set to continue next year.