Hillary Clinton tells a London audience she's worried that President Donald Trump could in 'a moment of pique' launch a nuclear missile.

The former Democratic presidential candidate accused the Trump of "picking fights" with North Korea and Iran for the sake of "point scoring."

Clinton added that Russia's interference in the 2016 election amounted to a "cyber 9/11."

LONDON — The former US Democratic presidential candidate Hillary Clinton says she is genuinely worried that President Donald Trump will in a moment of rage launch a nuclear missile.

Speaking at the Southbank Centre's London Literature Festival on Sunday evening, Clinton, who lost to Trump in last year's election, said Congress was "trying to figure out" how it could limit Trump's power to prevent a nuclear war.

Trump earlier this year threatened North Korea with "fire and fury like the world has never seen" after Pyongyang conducted a series of missile tests.

"A lot of people thought I was probably exaggerating it, but now we are worried and Congress is worried about whether they can take that power away from Trump so that in a moment of pique he doesn't pick up that phone and call whoever is sitting in the control centre today," Clinton told an audience of about 3,000 people, which included Mayor Sadiq Khan of London, Labour Party Deputy Leader Tom Watson, and former Deputy Prime Minister Nick Clegg.

"I tried to raise it before and I'm raising it again here. It's why members of Congress on both sides are trying to work out how they can contain [Trump]."

Asked whether she was concerned that Trump would launch a nuclear attack during his presidency, Clinton said: "I'm worried about that now. I had big differences with so many of the other people who have been president during my lifetime, but I never worried about that.

"Republicans and Democrats are scratching their heads trying to figure out how they interpose — maybe they'll say [a nuclear attack] has to be jointly signed off by the secretary of defence and the secretary of state. Some are even saying there should have to be a declaration of war [by Congress]."

Clinton went on to accuse Trump of "picking fights" with world powers like North Korea and Iran for the sake of "scoring points" and appealing to his voter base. Trump last week refused to support the Iran nuclear deal signed in 2015, describing it as "one of the worst and most one-sided deals."

Russian interference in US Election was 'cyber 9/11'

Clinton, who is touring the UK to launch her book "What Happened", said Russia's interference on last year's US election amounted to a "cyber 9/11," and she said Moscow was "not done" in tampering in Western democracies.

"We had really well-respected security, intelligence veterans saying this was a 'cyber 9/11' in the sense it was a direct attack on our institutions," she said.

"That may sound dramatic, but we know that they probed and tried to intrude into election systems — not just the social-media propaganda part of their campaign."

Clinton said that "a lot more connections have yet to come to light" and that she would have called for an independent commission "to get to the bottom of it" had she been elected.

"The Russians are not done — this is an ongoing threat," she warned, adding that Russian President Vladimir Putin would continue to try to influence the outcome of elections to expand his power across the world.

She accused Putin of sharing Trump's attitude toward women: "He doesn't like women very much. His behaviour around women. I've seen it in rooms with him. Condescending, insulting comments. He has a record of it."