A war of words between Tongan rugby-league players and their board has escalated.

Tonga NRL Chairman George Koloamatangi has told ABC Radio Australia stars like Andrew Fifita are "not the sharpest tools in the shed".

He's also dismissed players concerns about the financial management of the organisation, and accused senior players of intimidating members of the team.

The comments come as a group of Tongan NRL Star threaten to boycott all international fixtures, and follows a decision by the board sacked head-coach Kristian Woolf.