Anthony Mundine suffered the first cut of his boxing career before ending Darmel Castillo's hasty visit to Australia with a controversial fourth round knockout on the Gold Coast.

The 18th knockout of Mundine's career came with a flurry of punches thrown at Panama's Castillo, who argued he had been hit on the way down and wanted to fight on.

"If he'd got up I would have finished him anyway," said Mundine.

"I didn't know if he was on one knee. It was instinct. I'm not a dirty fighter."

A crowd of about 1,500 people also wanted the fight to continue and booed the decision by referee Cyril Cairns to rule the bout over.

Mundine suffered a cut to his left eyebrow during the third round.

"It's the first of my career. He got me with an upper cut. It just grazed me. He caught me as I was ducking down."

NSW boxing officials had refused to sanction the bout because of fears for the safety of the unheralded Castillo, forcing the event to be switched to Queensland.

Mundine selected Castillo when Manny Siaca, who took the world title from the former rugby league player last year, withdrew from a planned re-match with a hand injury.

The world No.253 showed courage but failed to land any solid shots on Mundine, who rattled the visitor from the opening bell.

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