US National Guard soldier Jack Teixeira, the suspect arrested in connection with a massive US classified documents leak, has been charged.

As CNN reports, Teixeira, who appeared in court in Boston on Friday, has been charged with unauthorised retention and transmission of national defense information, as well as unauthorised removal of classified information and defence materials.

Teixeira's next hearing has been set for Wednesday, April 19. The National Guard member did not enter a plea, but judges ordered that he should remain in detention until next week.

The 21-year-old Massachusetts Air National Guardsman was arrested by the Federal Bureau of Investigation on April 13.

Teixeira is believed to be the leader of the group where a trove of classified documents had been posted online. According to the media, he was the administrator of an online group in which he distributed secret Pentagon intelligence data, in particular, about Ukraine's defence capabilities.

A huge number of American intelligence documents have been published on social networks in recent weeks. The US Department of Justice has launched an investigation into the leak, which may last several months.

The US State Department says that the incident involving the publication of classified documents of the US Department of Defence will not affect support for Ukraine in its war with Russia.