Tony Blair has admitted he "underestimated" the challenges of entering a war in Iraq as he said the UK must be ready to send in ground troops to battle Islamic State (Isis) extremists.

The former Prime Minister said he had some regrets over his own intervention in Iraq after he declared war on the country despite significant opposition at home.

He said the West had failed to anticipate the chaos and instability that followed the removal of former dictator Saddam Hussein but stopped short of saying the invasion had been a mistake.

"We underestimated profoundly the forces that were at work in the region and that would take advantage of the change once you topple the regime," he said.

Mr Blair has previously said there are "elements of truth" in claims the Iraq war helped spur the rise of Isis.

When asked if the legacy of Iraq meant it was more difficult for a UK leader to deploy troops overseas, Mr Blair said: "You can describe it as a legacy or describe it as a fact that arises from the nature of the conflict."

The former Prime Minister said Britain must be prepared to conduct a "proper ground war" in Iraq, pitching UK troops against Islamic State militants who still control much of the country.

Mr Blair said the West must be willing to put boots on the ground in the Middle East to stop Isis before it makes significant inroads into Libya, where the terror group has been developing a growing base.

"This is where we have got to learn the lessons, not just of Iraq but what has come afterwards as well," he told an event in Westminster.

He stressed British forces could act in a supportive role to local troops who are currently struggling to repel the insurgents.

Mr Blair warned that it would be "profoundly irresponsible" to allow Isis to make inroads into Libya and creep closer towards Europe.