White House spokesman Spicer out in shake-up

White House press secretary Sean Spicer abruptly resigned on Friday, in protest at a major shake-up of Donald Trump's scandal-tainted administration, as pressure mounted from a broadening investigation into the Trump campaign's ties to Russia.

Spicer quit after Trump named Anthony Scaramucci, a Wall Street financier and one-time critic, as the new White House communications director - a role Spicer had hoped to play.

"It's been an honour & a privilege to serve @POTUS @realDonaldTrump & this amazing country. I will continue my service through August," Spicer tweeted.

In a written statement, Trump said he was "grateful" for Spicer's work and praised his "great television ratings" - a reference to Spicer's keenly watched, combative and often-satirised news briefings. 

Spicer was replaced by deputy press secretary Sarah Huckabee Sanders.

Spicer's resignation marked an escalation of tensions within an administration that has seen its legislative agenda falter at the same time it has been buffeted by an investigation into alleged collusion with Russia. 

On Friday, the Washington Post reported that Attorney General Jeff Sessions, contrary to his prior testimony, discussed campaign-related and policy matters with Russia's ambassador to Washington, citing intelligence intercepts.

The report will heap pressure on Sessions, who already was on the receiving end of a tongue-lashing by Trump over the Russia probe. The president suggested Sessions had betrayed him in stepping away from the investigation.

And in another blow, Mark Corallo - who was coordinating the Trump legal team's public response to the Russia crisis - told AFP that he, too, had stepped down.

After months of denials, the White House was recently rocked by emails showing Donald Trump's eldest son and two top aides met with a Russian lawyer in the belief they would get dirt on the Republican billionaire's 2016 election rival, Hillary Clinton.

In response, Trump aides have floated the idea of pre-emptive presidential pardons and Trump himself has warned investigators not to look into his family finances.

Spicer's decision appears to have happened quickly, with neither he nor Sanders giving any indication of changes afoot when they had drinks with a group of journalists on Thursday evening.

Spicer had "no regrets" on his way out the door, he said on Fox late Friday.

Yet he angrily lashed out at US media, claiming they were "obsessed" with Russia after US intelligence agencies said that Moscow was involved in meddling with the US presidential election Trump won. 

"I was increasingly disappointed in how so many members of the members here in the media do their job, or rather, don't do their job. The bias which they come from it at," Spicer said. 

And it is no exception, he stressed.

Spicer had been a close ally of chief of staff Reince Priebus, and his departure will likely weaken both Priebus and the bridge between the White House and the Republican Party establishment.