House Speaker Nancy Pelosi on Thursday called for US sanctions against Russia's intelligence service over bounties that it reportedly offered Taliban militants to kill American soldiers in Afghanistan.

The top Democrat in Congress also said the White House had opposed sanctions "that pertained to the intelligence and the defense sectors" of Russia in previous bipartisan legislation that was aimed at punishing Moscow.

Russian intelligence and defense comprise "the very sector that is accused of possible threats on our men and women in uniform" through the bounty scheme, Pelosi said.

"Whatever else happens of this, we must restore those sanctions and we must act upon them."

She also said Russia should be held accountable for seeking to "again" undermine US elections.

Pelosi was addressing reporters after a classified briefing by US intelligence officials about the bounty scheme, first reported by The New York Times, in which Russia allegedly offered rewards to kill troops of the US-led coalition in Afghanistan.

The White House said President Donald Trump had not been briefed on the intelligence because it was unverified. The Times, citing multiple officials, reported the intelligence was included in the written presidential daily brief back in February.

Pelosi would not be drawn on what was discussed in the classified briefing that she and other congressional leaders received. 

But she said "of course" the president should have been briefed on the matter directly even though the intelligence was not verified.

"This is of the highest priority: force protection," she said.

Trump "should spend more time reading the presidential daily brief than planning military parades and preserving the relics of the Confederacy," she added.

Pelosi joined Senate Democrats in seeking Russia sanctions.

Senator Robert Menendez on Wednesday introduced an amendment to a massive defense spending bill that would freeze the assets and ban visas for Putin and other Russian officials if they are found to be involved in offering rewards to kill US troops.