President Donald Trump was not briefed on reports that Russia offered bounties to Taliban-linked militias to kill US soldiers in Afghanistan due to concern over the accuracy of the intelligence, a White House spokeswoman said Monday.

"There is no consensus within the intelligence community on these allegations," Kayleigh McEnany said.

"In fact, there are dissenting opinions," she added, denying the president had been briefed on the explosive claims.

The New York Times report, citing anonymous officials, said Trump had been told about findings, which he has also denied.

Both Nancy Pelosi, the speaker of the House of Representatives, and Chuck Schumer, the Senate minority leader, called for an urgent briefing on the reports.

House Majority Leader Steny Hoyer said he and other senior Democrats had been asked to a briefing at the White House on Tuesday.

McEnany said the briefing "will clear up a lot of the false reporting from The New York Times." 

"The intelligence is verified before it reaches the President of the United States. In this case it wasn't verified," she said.

- 'Inexplicable behavior' -

In a letter released earlier and addressed to John Ratcliffe, the director of National Intelligence, and CIA director Gina Haspel, Pelosi said, "The questions that arise are: was the president briefed, and if not, why not, and why was Congress not briefed."

Ratcliffe responded Monday evening, saying in a statement: "We are still investigating the alleged intelligence referenced in recent media reporting and we will brief the President and Congressional leaders at the appropriate time."

"Unfortunately," he said, "unauthorized disclosures now jeopardize our ability to ever find out the full story with respect to these allegations."

The Times report, which has been confirmed by several American and British media outlets, said that US intelligence concluded that a Russian military intelligence unit offered rewards to Taliban-linked militants to kill troops of the US-led coalition in Afghanistan.

The rewards were purportedly incentives to target US forces as Trump tries to withdraw troops from the conflict-torn country -- one of the militants' key demands -- and end America's longest war.

Pelosi, the top Democrat in Congress, asked the intelligence chiefs to hold an interagency briefing on the reports and "President Trump's inexplicable behavior towards Russia."

"Congress and the country need answers now," Pelosi said, adding that the briefing should also focus on "what options are available to hold Russia accountable."

Schumer, the Democratic leader in the Senate, echoed her call.

"We need to know whether or not President Trump was told this information, and if so, when," he said.

Trump on Sunday denied having been briefed on the matter, as the report renewed questions about his reluctance to confront Russia.

"Intel just reported to me that they did not find this info credible, and therefore did not report it to me or @VP," he tweeted.

But even in Republican ranks, there were expressions of concern at the gravity of the allegations.

"If intelligence reports are verified that Russia or any other country is placing bounties on American troops, then they need to be treated as a state sponsor of terrorism," tweeted Thom Tillis, a Republican on the Senate Armed Forces committee.

According to official Pentagon figures, no member of the US armed forces has been killed in Afghanistan since late March.