Roger Stone speaks to members of the conservative group America First at the Marriott in Boca Raton, Florida: Michael Ares/Palm Beach Post/AP

One of Donald Trump's closest advisers has warned a bloody civil war would erupt if the US President was impeached.

Roger Stone predicted "an insurrection like you've never seen" if politicians sought to remove the US leader from the White House and claimed any politician who voted to topple him "would be endangering their own life".

Talk of impeachment has endured throughout Mr Trump's presidency amid allegations of collusion between Russia and the billionaire Republican's election campaign.

Support for his removal from office has risen to 40 per cent among the American public, according to a poll by the Public Religion Research Institute (PRRI) earlier this month.

But Mr Stone, a long-time Trump confidant and former official in Richard Nixon's administration, suggested impeachment proceedings would lead to an armed uprising among the President's supporters.

"Try to impeach him, just try it. You will have a spasm of violence in this country, an insurrection like you’ve never seen," he told entertainment website, TMZ. "The people will not stand for impeachment. A politician that votes for it would be endangering their own life."

Asked if he believed there would be "some sort of civil war" if the President was impeached, he replied: "Yes, that's what I think will happen.

"Both sides are heavily armed... There would be violence on both sides."

The Republican strategist and self-proclaimed "dirty trickster" claimed he was "not advocating violence" but "predicting it".

Mr Stone, who was an adviser to Mr Trump's presidential campaign and is thought to still speak to him regularly, said: "The people who are calling for impeachment are the people who didn't vote for him. They need to get over it, they lost."

He added: "Sorry, he whipped Hillary Clinton's ass. It's over, you lost."

A former US labour secretary this week became the latest high-profile Trump critic to call for his impeachment.

Robert Reich said the President was a "clear and present danger to America" and must be removed from office.

Democrat Representative Steve Cohen last week said he intended to introduce articles of impeachment against Mr Trump over his response to white supremacist violence in Charlottesville, Virginia.