Washington (CNN) An American citizen being held by the United States in Iraq for allegedly fighting for ISIS said he traveled to Syria to work as a journalist and chronicle what life was like under the terror group, according to newly released court documents.

The unnamed American, who is also a citizen of Saudi Arabia, was captured in Syria last September by the Syrian Democratic Forces, an American-backed militia, and handed over to US authorities in Iraq. He has challenged the legality of his detention and is also contesting the government's position that it may also lawfully transfer him to a third country.

The individual is currently being represented by the American Civil Liberties Union.

According to the documents released Wednesday, an unnamed FBI agent writes that search warrants issued for an email account used by the prisoner show he communicated with an unnamed press accreditation agency, and later indicated in an email that he "planned to cover various events and stories in a number of areas/countries in the Middle East," and that he had "gathered a great deal of information living in refugee tents on the Turkish-Syrian border" and requested a link to upload his written articles.

However, the declaration from the FBI official questioned whether the individual had a real desire to report stories from the region.

Read More