Tonga's police commissioner, Grant O'Fee, says it will take many years before the culture of violence within the police force can be eliminated.
A police investigation has begun into a video posted online that allegedly shows a police officer countinuously punching and kicking a boy at a rugby game last week.
This comes less than a month after police officers were imprisoned for the manslaughter of New Zealand constable Kali Fungavaka.
Mr O'Fee says offenders will continue to be brought to account and punished, but there is a long way to go to get rid of such behaviour.
"To get that change in the way our officers behave and, I hate the word, but the culture of the organisation, it's gonna take years and years and years, it will not happen in months or weeks or even years, it will take many many years. I guess it's just not the time to lose our nerve, we just have to keep on doing what we have been doing and the change will come but it will take time."
Tonga's police commissioner, Grant O'Fee.
The officer alleged to have been involved in the video assault has been indentified.