WASHINGTON — The US government on Thursday accused Russia of carrying out a "pervasive" campaign to influence public opinion and elections, in a warning just months before crucial legislative polls.

"We continue to see a pervasive messaging campaign from Russia to try to weaken and divide the United States," said Dan Coats, the director of national intelligence.

A slew of top US officials including Coats, FBI Director Christopher Wray and Homeland Security chief Kirstjen Nielsen vowed to investigate and prosecute those who were trying to sway US opinion or carrying out what Wray described as "information warfare."

"Our democracy itself is in the crosshairs," Nielsen said in an unusually stark warning.

"This is not just an election cycle threat," Wray said. "Our adversaries are trying to undermine our country on a persistent and regular basis, whether it’s election season or not."

Coats pointed the finger of blame at the Kremlin: "Russia has used numerous ways in which they want to influence... through media, social media, through bots, through actors that they hire, through proxies."

The comments came in jarring contrast to the positions of President Donald Trump, but the two men dismissed suggestions the president – who has repeatedly denied Russia moved to tilt the election in his favor – is not taking the issue seriously.

In a letter to Congress, National Security Advisor John Bolton said the administration had taken "extensive, historic action" to stop the threat.

Trump has mulled easing sanctions against Moscow, held warm meetings with Russian President Vladimir Putin and refused to criticize him over the meddling in the 2016 election.

He has also repeatedly called for an end to the investigation into Moscow’s meddling, which has seen more than 20 Russians indicted so far.

“Opinion”, not order

On Wednesday Trump told his attorney general to end the high-profile investigation, led by former FBI director Robert Mueller.

"This is a terrible situation and Attorney General Jeff Sessions should stop this Rigged Witch Hunt right now, before it continues to stain our country any further," Trump said.

Aides rushed to limit the damage, insisting he was not issuing an order as Session’s boss.

"It’s not an order, it’s the president’s opinion," White House spokeswoman Sarah Sanders told reporters, adding that Trump wants the probe to "come to an end."

Mueller is investigating whether the Trump campaign aided or abetted an attempt by Russia to sway the 2016 presidential election, or tried to cover up the conspiracy.

Asked whether the administration could be trusted to protect the country, Wray responded: "I can assure the American people that the men and the women of the FBI, from the director all the way on down, are going to follow our oaths and do our jobs."

Republican Senator John McCain was among those who called on the US government to do more than warn the public.

"Our top intelligence officials have repeatedly warned that #Putin continues to target our elections & sow chaos," he tweeted. "Until he pays a price, these attacks will grow."

Congress is currently considering a sanctions bill designed to deter Russia. — AFP