The Public Service Association in Tonga says it will take its concerns of possible unlawful conduct by the Prime Minister, Lord Tu'ivakano, to the King.
The PSA's general secretary, Mele 'Amanaki, says Lord Tu'ivakano made an unlawful payment of 18 million US dollars to the country's satellite communication provider, Tongasat, in 2011.
Ms 'Amanaki says it gave the Prime Minister a total of eight weeks to voluntarily resign over the matter, but that period ended last Friday.
She says the PSA has been forced to take the matter to a higher authority.
"We will take our concerns to the King, through a petition. We will continue on calling for the Prime Minister to resign, we will let the King decide on that under his constitutional rights, if he thinks the same as us."
Mele 'Amanaki says it has also submitted an appeal to the Public Service Tribunal for its proposal on the recent Cost Of Living Adjustment to be reconsidered.
She says Cabinet previously refused to discuss its proposal.
