First charges filed in probe into claims of Russian meddling and Trump campaign collusion

The indictment was sealed under orders from a federal judge so it was not clear what the charges were or who the target was, the source said, adding that it could be unsealed as early as Monday.

The filing of charges in Washington was first reported by CNN, which said the target could be taken into custody on Monday.

US intelligence agencies concluded in January that Russia interfered in the election to try to help President Donald Trump defeat Democratic candidate Hillary Clinton through a campaign of hacking and releasing embarrassing emails, and disseminating propaganda via social media to discredit her campaign.

Special counsel Robert Mueller, a former director of the Federal Bureau of Investigation, is investigating whether Trump campaign officials colluded with those alleged Russian efforts.