Mike Tyson has claimed he would ‘kick Conor McGregor’s a**' inside a boxing ring.

The 53-year-old heavyweight recently announced his return to the sport in an exhibition fight with Roy Jones Jr on September 12.

And 'Iron Mike’ has immediately returned to his outspoken, no nonsense trash talk by insisting he would batter UFC star McGregor in the ring.

Speaking on The Tonight Show with Jimmy Fallon, he said: "Imma kick his a** anyway, we'll play boxing rules."

The dig came as something of a surprise as Tyson had previously praised McGregor for his efforts against Floyd Mayweather in 2017 when he was stopped in the tenth round.

Tyson said of the Irishman’s performance: "He never really had a boxing match in his life, right. He went 10 rounds with the greatest fighter in the last 100 years of boxing.

"He went 10 rounds, scored punches on the greatest boxer in the last 100 years.

"Did he do something? Did he accomplish something? People should look who he had the fight against and look what he did when he fought against him."

McGregor then replied with a sincere statement to the legendary heavyweight, saying: "Thank you Mike and just know that for the inevitable rematch, with the knowledge I now hold of Floyd’s style, plus under the tutelage of my old school boxing coach, I will crack the puzzle, and I will beat Floyd. I promise my life on it.

"It’s great to see you back Iron Mike."

McGregor announced his retirement from the UFC last month, with his last fight coming in a 40-second victory over Donald Cerrone back in January.