The scale of the deep divisions at the top of the Labour Party have been laid bare as shadow cabinet ministers put themselves on a collision course with the new leader over a series of crucial issues.

Jeremy Corbyn, an anti-war campaigner, opposes the replacement of the nuclear weapons system and has questioned the role of the Nato.

But senior party figures have described his victory as an "earthquake" for the party and set out policy red lines that put them at odds with the new leader.

Lord Falconer, a close friend of Tony Blair who served in the former prime minister's government, said he had "no idea" if Mr Corbyn would be prime minister following the 2020 general election.

The shadow justice secretary - who revealed he spoke to Mr Blair before taking up his new post - told BBC One's Sunday Politics: "What's happened is an earthquake in the Labour Party."

Lord Falconer set out his disagreements with Mr Corbyn's views on a wide range of policy areas, including defence, foreign affairs, welfare, education and the economy.

He said during the course of the leadership election that, for example, he might think about withdrawing from Nato.

"That would obviously be something I could not agree with," he said.

Lord Falconer said he was in favour of renewing Trident but said it was for the party to debate the issue.

The peer also hit out at new shadow chancellor and close ally of Mr Corbyn, John McDonnell, over his suggestion that Tony Blair should be arrested for war crimes following the Iraq conflict.

“I'd say that's complete nonsense – obviously. I mean, Tony Blair is not a war criminal. That's just off the page... It wasn't an illegal war."

He also said the party should not apologise for taking the UK into the Iraq war, but conceded it was a matter for the leader to decide.

In a further clash with Mr McDonnell, who last week was forced to apologise over 2003 comments regarding the IRA, claiming he was only trying to help the peace process, Lord Falconer said he "wasn't personally aware" that Mr McDonnell had anything to do with it.

His decision to disclose his policy red lines came after shadow foreign secretary Hilary Benn set out his support for Trident and Nato.

Mr Benn said military alliance was the "cornerstone of our security" and insisted he did not see Britain withdrawing.

He told BBC One's Andrew Marr Show: "My view is that we need to maintain an independent nuclear deterrent."