A US senator said on Wednesday that Russia needed to understand it had taken one step too far during the presidential election won by Donald Trump.

"It is now time for Russia to understand – enough is enough," Republican Senator Lindsey Graham of South Carolina said in the Latvian capital.

Earlier this month, US Republican and Democratic senators including Graham called for a special bipartisan panel to investigate cyber attacks against the United States by foreign countries with a focus on Russia's alleged efforts to influence the US presidential election.

Russian officials have denied accusations of interference in the Nov 8 election.