Transparency International in Vanuatu says the alleged attack by public works minister, Harry Iauko, on a newspaper publisher, shows he's unfit for public office.
In a media statement, the watchdog body says the attack on the Daily Post's Mark Neil-Jones is the latest in a line of unwise or allegedly corrupt actions by the minister.
It says if the Sato Kilman government wants to retain credibility, swift and decisive sanctions will need to be taken against Mr Iauko.
Transparency says the minister is in his position to serve the public, not help himself to whatever he wants, either for himself or for his political cronies, and certainly not to assault people who are doing their job.
It also asks whether any of the serious allegations raised in the media about Mr Iauko's been shown to be wrong.
It says if the Minister felt he'd been defamed he could sue.