After hundreds of thousands killed, Tony Blair says illegal Iraq invasion 'may have been wrong'

Former UK Prime Minister Tony Blair has said he "may have been wrong" over his decision to launch invasions of Iraq and Afghanistan, which left hundreds of thousands dead.

Blair made the confession to the Anglican Church's Archbishop of Canterbury Justin Welby on BBC Radio 4, in which he spoke of the controversial decisions - deemed illegal by much of the world - to go war.

"People often say over Iraq or Afghanistan that I took the wrong decision but you've got to do what you think is right," the former premier said.

"Whether you are right or not is another matter. In those really big decisions, you don’t know what all the different component elements are, and you've got to follow, in the end, your own instinct."

He conceded that the decision "may have been wrong" but insisted that he "had to do what I thought was the right thing".

Blair, the UK Labour Party's most successful leader, has long defended his involvement in the US-led so-called War on Terror.

The invasion of Afghanistan in 2001 and Iraq in 2003 have tainted his political legacy, which includes securing peace in Northern Ireland, investing in the UK's health and education systems, and expanding gay rights.

Critics of the former leader accuse him of war crimes and point to the now-debunked evidence on which the UK based its 2003 Iraq invasion, which claimed that Iraqi dictator Saddam Hussein had acquired weapons of mass destruction.

Queen Elizabeth II's recent decision to appoint Blair the UK's most senior order of knighthood sparked fury among the British public, with a Change.org petition opposing the decision gathering more than one million signatories.

In response to criticism, Blair said that his leadership should be remembered for more than the Iraq war.

"There are some people who want to say the only thing the government did was Iraq and ignore all the rest of the things we do," he said at the time.