US government contractor accused of stealing classified information.

A US federal government contractor has been accused of removing highly classified information and storing the material in his house and car, federal prosecutors announced.

The Justice Department announced a criminal complaint against Harold Thomas Martin III of Glen Burnie, Maryland.

The Justice Department's top national security official, John Carlin, said in Boston that the arrest pointed to the threat posed by insiders.
Among the classified documents, the government says, were six that contain sensitive intelligence - meaning they were produced through sensitive government sources or methods that are critical to national security issues - and date back to 2014.

All the documents were clearly marked as classified information, according to the criminal complaint.

Investigators also found stolen property valued at more than 1,000 US dollars at Martin's residence or vehicle. He voluntarily agreed to an interview.

"Martin at first denied, and later when confronted with specific documents, admitted he took documents and digital files from his work assignment to his residence and vehicle that he knew were classified," according to the complaint, despite not having the authorisation to do so.

Martin has been in custody since a court appearance in August.

Speaking at a cybersecurity panel, the Justice Department's top national security official, John Carlin, confirmed the arrest of "an individual who's involved in taking classified information".

The complaint charges Martin with unauthorised removal and retention of classified materials, which carries a maximum one-year sentence, and theft of government property - an offence punishable by up to 10 years.