Electing Labour's Jeremy Corbyn to lead the UK as prime minister would be a "very dangerous experiment", according to the party's longest serving leader Tony Blair. Rather than veer to the left, he said the party needed to reclaim the centre ground of British politics.

Blair, who is expected to be heavily criticised when Sir John Chilcot's long-awaited report into the UK's involvement in the 2003 Iraq war is published on 6 July, has criticised Corbyn in the past. Before Corbyn won the party leadership, Blair warned that the party risked "annihilation" if the left-wing MP was victorious.

Dismissing the idea that Corbyn's election was a rejection of him and his policies, Blair told the BBC's This Week's World that it was "a result of the way the world works these days" and it was a "big challenge for the centre".

"It would be a very dangerous experiment for a major western country to get gripped by this type of populist policy-making, left or right," he said.

He also insisted that he had "real humility" about the decisions he took on Iraq, saying that it was "very tough" as he was trying to deal with it in the aftermath of 9/11.

Blair, who served as Labour leader from 1994-2007, and prime minister for 10 of those years, is expected to be criticised in the Chilcot report, which was set up in 2009 by Gordon Brown as an inquiry into a war that started in 2003.

While Blair said he would not comment on the report until its publication, he warned that there will be bigger terrorist attacks on Europe in the future.

"You've got to open your eyes to the problem," he said. "If we don't do that we're going to store up an even bigger problem for ourselves, and we face the problem in Europe, I'm afraid, of even bigger terror attacks."

"I think we need to be in no doubt at all about the people we're dealing with here," he added. "If they could kill larger numbers of people that's what they would do."