(Adds senator's comment, call for sanctions, paragraphs 7-8)
By Patricia Zengerle
WASHINGTON, Feb 16 (Reuters) - U.S. Republicans and Democrats both called for concerted action to combat foreign interference in U.S. elections after Special Counsel Robert Mueller announced indictments of Russians for meddling in the 2016 U.S. campaign on Friday.
"These Russians engaged in a sinister and systematic attack on our political system," Paul Ryan, the Republican Speaker of the House of Representatives said in a statement calling the suspects' actions a conspiracy targeting democracy.
"Today’s announcement underscores why we need to follow the facts and work to protect the integrity of future elections," Ryan said.
Senator Mark Warner, the top Democrat on the U.S. Senate Intelligence Committee, pledged to press social media companies "to be far more aggressive and proactive in responding to this threat."
The bipartisan calls for action were a departure from weeks of bickering between the two parties over the Russia investigations, which raised questions about whether Congress would be able to make credible recommendations about how to combat future election meddling.
The office of the special counsel charged 13 Russians and three Russian companies.
Some Democrats said the indictments should end President Donald Trump's insistence that Russian meddling was "fake news." "This is a VERY well done hoax," Senator Brian Schatz said on Twitter in a jab at President Donald Trump.
Other lawmakers called for the immediate imposition of sanctions on Russia that Congress passed overwhelmingly last year that Trump has yet to enact.
In addition to Mueller's probe, three congressional committees are investigating Russia and whether Trump associates colluded with Moscow.
Russia denies meddling, and Trump has repeatedly denied any collusion, most recently on Friday.
Some Republicans want Mueller to resign, although others have joined Democrats in calling for legislation to prevent Trump from firing him.
Republicans on the House Intelligence Committee wrote a memo accusing federal investigators of bias against Trump in obtaining a surveillance warrant. Democrats were furious after Trump declassified the Republican document but refused to make public their own memo seeking to debunk it.
On Friday, Representative Devin Nunes, the Republican chairman of House Intelligence, who commissioned the Republican memo, said it was "gratifying" to see the indictments, calling Russian President Vladimir Putin's government "a pressing threat to American interests."
Representative Adam Schiff, the panel's top Democrat, called the indictments "a significant step forward." He also said the indictment "leaves open the vital question of whether Americans, including any associated with the Trump campaign, knowingly played a role in Russia’s active measures campaign." (Reporting by Patricia Zengerle; editing by Grant McCool)