Tony Blair has apologised for mistakes made over the Iraq War - and said there were "elements of truth" to claims the war caused the rise of Islamic State.
The ex-PM said "those of us who removed Saddam" did bear some responsibility for the situation in Iraq today.
But he again defended the invasion, saying it was "hard to apologise" for removing Saddam Hussein and that Iraq might have become like Syria otherwise.
Scottish First Minister Nicola Sturgeon said it was a "Blair spin operation".
Mr Blair's comments come shortly before Sir John Chilcot announces a timetable for completion of his inquiry into the war.
He suggested that if the Iraq invasion had not taken place the country could have degenerated into civil war, as Syria did.
Most significant, though, in terms of new revelations is the former prime minister's admission that getting rid of Saddam Hussein may have had some bearing on the rise of so-called Islamic State.
One other thing is notable; Tony Blair appears to believe that the UK and Europe's current military inaction over Syria is wrong.
He also apologised for "some of the mistakes in planning" as well as "our mistake in our understanding of what would happen once you removed the regime".
Asked if the war was the "principal cause" of the rise of the so-called Islamic State (IS or ISIS) militant group, he replied: "I think there are elements of truth in that.
"Of course you can't say those of us who removed Saddam in 2003 bear no responsibility for the situation in 2015, but it is important to also realise that the Arab Spring which began in 2011 would have also had its impact on Iraq today."
But relative stability in Iraq in 2009 was then undermined by "sectarian" policies of the then Iraqi government and the impact of the Arab Spring, he said.
Mr Blair said IS then moved from Iraq into Syria and established itself there, before returning to Iraq.