Britain would be embarking on a "very dangerous experiment" if it gave Labour leader Jeremy Corbyn power, former prime minister Tony Blair has warned.
The ex-Labour premier also said he has "real humility" about the decisions he took over Iraq and hopes the long-awaited Chilcot report into the war will provoke a wider debate.
Asked if Mr Corbyn was a product of his, Mr Blair told the BBC's This Week's World: "No, I think it's a result of the way the world works these days, but it's a big challenge for the centre, and when I'm not thinking about the Middle East, I'm thinking about this because I do think, by the way, 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.
"I do think the centre ground needs to work out how it recovers its... gets its mojo back, and gets the initiative back in the political debate because otherwise... these guys aren't providing answers, not on the economy, not on foreign policy."
Mr Blair insisted he had to take tough and difficult decisions over Iraq.
"I have a real humility about the decisions that I took and the issues around them and... you know, I was trying to deal with this in the aftermath of 9/11 and it was very tough, it was very difficult," the ex-PM said.
Ahead of publication of the Chilcot report on July 6, Mr Blair insisted the West was not to blame for the situation in the Middle East as he warned of bigger terrorist assaults on Europe.
"You've got to open your eyes to the problem, and 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 and I think we need to be in no doubt at all about the people we're dealing with here.
"If they could kill larger numbers of people that's what they would do. So, this is a different type of threat from anything we have faced before, it requires a different type of policy response and it requires a different rhythm of thinking where we understand this is a generation fight, it's not a fight that's going to be resolved in one year, two years, or even 10," Mr Blair said.
Former Labour leader Ed Miliband refused to be drawn on Mr Blair's remarks at a Remain campaign event.