TONY Blair “underestimated” the consequences of waging war in Iraq in a move which led to the rise of Daesh, he admitted yesterday.

The former prime minister conceded the 2003 invasion to topple Saddam Hussain had contributed to the growth of the Islamist terror group at an event in Westminster yesterday.

The long-delayed Chilcot report is expected to be heavily critical of Blair on its release in July.

Yesterday Blair said he failed to appreciate the complexities of the region when he committed British troops to the bloody war, which led to the deaths of 179 service personnel and thousands of civilians.

The ex-Labour leader said: “We underestimated profoundly the forces that were at work in the region and would take advantage of change once you topple the regime. That is the lesson.

“The lesson is simple. It is that when you remove a dictatorship out come these forces of destabilisation, whether it is al Qaeda on the Sunni side or Iran and its militia on the Shia side.”

Blair went on: “To be honest, my understanding of the Middle East is a lot deeper today than it was when I was prime minister.”

Speaking at an event sponsored by Prospect magazine, Blair said the fall of a dictator gives rise to “poisonous forces and influences” and there are “elements of truth” to claims that the fallout from the Iraq war had contributed to the growth of Daesh.

However, he stressed it did not cause its formation and that there had been more than one influence in its development. Repeating his call for a “proper ground war” to defeat Daesh, Blair said: “Airstrikes are not going to defeat Isis. It does not mean it has to be our forces all the time, it could be that our forces are in support.

“But be in no doubt, if you want to defeat these people you are going to have to wage a proper ground war.”

Praising the actions of the US military and other allies, Blair indicated the Iraq war had made it more difficult for the UK to deploy troops abroad:“You can describe it as a legacy or describe it as a fact that arises from the nature of the conflict,” he said.