US Attorney General Jeff Sessions discussed campaign-related issues with the Russian ambassador to Washington during the last year's presidential race, a claim Sessions has denied various times, according to a report by The Washington Post.

The paper quoted on Friday current and former administration officials who cited US intelligence intercepts of Sergey Kislyak's accounts to his bosses in Moscow of two encounters he had with Sessions, then an adviser to Trump, during the campaign.

Sessions at first failed to disclose his contacts with Kislyak and then said the meetings were not about the Trump campaign.

The new claim is certain to add more pressure on Sessions, whose job security is seen as being in jeopardy after President Donald Trump criticised him in scathing terms in an interview this week with The New York Times, saying he was sorry he had hired him.

Trump said he regretted the hiring because Sessions in March recused himself from overseeing an FBI-led probe into Russian meddling to favour Trump during the US presidential election.

Sessions had denied claims

Sessions recused himself after it was disclosed that he had, in fact, met the ambassador during the campaign, after saying during his confirmation hearing that he had not met any Russian officials during that period.

Sessions insisted when he recused himself that he had not talked about the US election campaign with the ambassador.

"I never had meetings with Russian operatives or Russian intermediaries about the Trump campaign," he said at the time.

READ MORE: Jeff Sessions calls Russia claims a 'detestable lie'

However, Kislyak, in briefing his superiors on the meetings, said he and Sessions discussed campaign-related matters including policy issues important to Moscow, the Post said.

It quoted one former official as saying the intercepts suggest Sessions and Kislyak had "substantive" talks on issues including Trump's positions on Russia-related subjects and prospects for bilateral relations in a Trump administration.

Al Jazeera's Alan Fisher, reporting from Washington, DC, said Sessions was now challenged having already denied having discussions with Russians about the Trump campaign, at his confirmation hearing in the Senate.

"If the report is true, he is in real trouble. He had to correct his account before. If he does it again, essentially it will be the end for Sessions," he said.

A US official also confirmed to the Reuters news agency on Friday Kislyak's intercepted accounts of two conversations with Sessions.

The official, who spoke on condition of anonymity, said there was nothing automatically inappropriate about Sessions discussing policy matters, or even Trump's views about them, with a foreign diplomat.

"The question is whether he crossed the line and discussed classified information or talked about deals like lifting sanctions, if the Russians were interested in investing in the US, or had dirt on Secretary [Hillary] Clinton," said a second official familiar with the intercepts, who also spoke on the condition of anonymity. "His memory is another matter."