LONDON — Tony Blair, the former British prime minister, suggested on Sunday that the United States-led invasion of Iraq in 2003, which removed Saddam Hussein from power, helped give rise to the Islamic State, even as he said it was “hard to apologize for removing Saddam.”

Mr. Blair, whose decision to involve Britain in the military mission made him deeply unpopular at home, told CNN that “there are elements of truth” to the view that the war in Iraq helped pave the way for the Islamic State.

The militant group emerged as an offshoot of Al Qaeda in Iraq, which fought the American presence there, before separating from the organization. It now controls vast swaths of territory in Iraq and Syria, and is also known as ISIS or ISIL.

“Of course, you can’t say those of us who removed Saddam in 2003 bear no responsibility for the situation in 2015,” Mr. Blair said in an interview with Fareed Zakaria broadcast on Sunday. “But it’s important also to realize, one, that the Arab Spring which began in 2011 would also have had its impact on Iraq today, and two, ISIS actually came to prominence from a base in Syria and not in Iraq.”