Washington, Apr 15 (IANS): The US air national guardsman suspected of leaking a trove of classified intelligence documents pertaining to national defence has been officially charged under the Espionage Act for allegedly posting the sensitive material online.

During his first court appearance on Friday at the US District Court for the District of Massachusetts, 21-year-old Jack Teixeira was informed of the two charges he faced: unauthorized retention and transmission of national defence information and unauthorised removal and retention of classified documents or material, Xinhua news agency reported citing court documents.

Teixeira will remain detained through the next court hearing on April 19.

The airman was arrested "without incident" by FBI agents on Thursday afternoon at his mother's home in North Dighton, Massachusetts, US Attorney General Merrick Garland told reporters at a news briefing.

According to publicly available information, Teixeira enlisted in the Massachusetts Air National Guard in 2019.

His job title is Cyber Transport Systems journeyman, and he has been promoted to the junior rank of Airman 1st Class.

Teixeira is the leader of a private online chat group where the classified documents -- numbering more than 100 pages -- first appeared in January.

From that point on, the material was widely circulated on a number of social media platforms, undetected by the federal government until early April.

Teixeira was granted Top Secret security clearance in 2021 and was said to have begun posting classified information online since December 2022, according to an affidavit submitted by investigators.

Defence Secretary Lloyd Austin, who until April 6 had been unaware of the leak, has ordered a review of the "intelligence access, accountability and control procedures" within the Department, according to a statement released on Thursday evening.

The dozens of leaked documents had revealed US assessments of the war in Ukraine as well as sensitive secrets about American allies.

The leaks embarrassed Washington and raised fresh questions over the security of classified information.