Melbourne Storm and Tongan forward Eliesa Katoa has undergone surgery overnight and remains in a stable condition after suffering seizure activity.

Katoa was taken to hospital in Auckland on Sunday during Tonga's clash with New Zealand after suffering repeated knocks to the head.

He required oxygen as he left the ground.

The Storm provided a medical update on Katoa on Monday morning, confirming he had suffered seizure activity on the bench after being removed from the field of play.

"Melbourne Storm forward Eli Katoa was taken to hospital after suffering seizure activity on the bench during the second half of yesterday's Pacific Championships match between Tonga and New Zealand," the club wrote.

"Eli underwent surgery overnight and is in a stable condition being supported by his partner and mother. Storm medical staff remain in close contact with the hospital and Tonga's team Chief Medical Officer.

"The Club will provide a further update as additional information becomes available."

AAP's Scott Bailey is claiming the surgery was to release fluid and pressure on the brain after he suffered a brain bleed.

It's unclear how long Katoa will be out for as he continues his recovery.

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