Tony Blair has apologised for aspects of the Iraq War, sparking claims of attempted "spin" ahead of the Chilcot Inquiry findings.
The former prime minister used a US television interview to express regret over the failure to plan properly for the aftermath of the 2003 toppling of Saddam Hussein and the false intelligence used to justify it.
"I apologise for the fact that the intelligence we received was wrong," he told CNN.
"I also apologise for some of the mistakes in planning and, certainly, our mistake in our understanding of what would happen once you removed the regime."
Asked by host Fareed Zakaria if the Iraq War was "the principal cause" of the rise of Islamic State, he was reported by the Mail on Sunday to have conceded: 'I think there are elements of truth in that."
He added: "Of course you can't say those of us who removed Saddam in 2003 bear no responsibility for the situation in 2015."
Scottish First Minister Nicola Sturgeon accused the ex-PM of starting to prepare the ground for expected criticisms when the long-delayed report of the Chilcot Inquiry is finally published.
"The Blair spin operation begins but the country still awaits the truth," the Scottish National Party leader posted on Twitter.
"The delay to Chilcot report is a scandal."
No date has yet been given for the release of the final conclusions - more than six years after the inquiry was set up by then prime minister Gordon Brown with an assurance it would take a year.
The process was severely delayed by a process known as "Maxwellisation", under which those who may face criticism - believed to include Mr Blair - are given the opportunity to respond before publication.
Relatives of soldiers killed in the conflict have threatened legal action if a date is not fixed soon.
A spokeswoman for the former PM said: "Tony Blair has always apologised for the intelligence being wrong and for mistakes in planning. He has always also said, and says again here, that he does not however think it was wrong to remove Saddam.
"He did not say the decision to remove Saddam in 2003 'caused ISIS' and pointed out that ISIS was barely heard of at the end of 2008, when al Qaida was basically beaten.
"He went on to say in 2009, Iraq was relatively more stable. What then happened was a combination of two things: there was a sectarian policy pursued by the government of Iraq, which were mistaken policies.
"But also when the Arab Spring began, ISIS moved from Iraq into Syria, built themselves from Syria and then came back into Iraq.
"All of this he has said before."
Lord Blunkett - who was home secretary at the time of the decision to join the military action - said he had sought assurances in vain from Mr Blair over the planning for the aftermath.
"Tony was not able to say what was going to happen when combat operations were over. He just decided to trust Cheney and Rumsfeld," he told the Mail on Sunday - referring to the then US vice president and defence secretary.
"With the benefit of hindsight, we now know that they had decided to embark on the complete de-Ba'athification of Saddam's Iraq by dismantling the entire government infrastructure.
"This led to the disintegration of any form of functioning government, creating a complete power vacuum. Terrorists infiltrated Iraq and stirred discontent.
'I am not seeking to scapegoat Tony Blair; we were all collectively to blame for deluding ourselves into believing that we had much greater sway over Washington," he said.
If Sir John Chilcot did not quickly release an interim copy of his findings, he woud "risk his entire exercise being entirely discredited", he added.