Washington: Hillary Clinton's campaign struck back at assertions by Russian President Vladimir Putin that the hacking of Democratic Party groups was a public service and accused him of endorsing "foreign interference" in the US presidential election.

Clinton spokesman Jesse Lehrich said experts have concluded Russia was behind the hacking of Democratic National Committee e-mails that were released by WikiLeaks just before the former secretary of state was to formally accept the party's nomination. Lehrich sought to draw a connection to Republican nominee Donald Trump's campaign.

"Unsurprisingly, Putin has joined Trump in cheering foreign interference in the US election that is clearly designed to inflict political damage on Hillary Clinton and Democrats," Lehrich said in an e-mail. "This is a national security issue and every American deserves answers about potential collusion between Trump campaign associates and the Kremlin."

Lehrich was reacting to Putin's remarks in a Bloomberg News interview in which he called the DNC breach and subsequent publishing of the documents a service to the public. The release led to the resignation of top DNC officials and became a distraction for Clinton just before the Democratic convention in July.