President Donald Trump has acknowledged that Russia conducted an "anti-US campaign" in the wake of an indictment accusing 13 nationals of meddling in the US presidential election.

The indictment, issued by the US Department of Justice, accuses the Russian nationals and three Russian entities with attempting to sway the election in Mr Trump's favour. In a tweet, the President said the indictment was further proof that his campaign had not colluded with Russia.

"Russia started their anti-US campaign in 2014, long before I announced that I would run for President," he wrote. "The results of the election were not impacted. The Trump campaign did nothing wrong - no collusion!"