The Tongan opposition leader, Akilisi Pohiva, says a law has been passed by parliament only to serve the interests of two of its noble representatives.
Parliament has voted to reduce the penalties for the illegal possession of firearms from seven years imprisonment to only one year, as well greatly reducing the fines that can be imposed.
Lord Tui'ilakepa and Lord Tu'iha'ateiho, who voted for the amendment, have been charged with illegal possession of a firearm and are awaiting trial.
Mr Pohiva, who voted against the bill, says there is no doubt there is a link.
"There must be some connection between these two cases and the legislation to minimise or reduce the penalty from seven to one."
Akilisi Pohiva says a law change doesn't make sense given gun related crime is on the rise in Tonga.