The Public Service Association in Tonga is calling for the Prime Minister to resign because of allegedly unlawful payments he made to the country's satellite communication provider, Tongasat.
The general secretary, Mele 'Amanaki says Lord Tu'ivakano made a payment of 18-million US dollars to the company in 2011, which is part owned by the King's sister, Princess Pilolevu Tuita.
Mrs 'Amanaki says she wrote to the Prime Minister six weeks ago recommending him to voluntarily resign over the payment, but has had no response.
She says it has given the Prime Minister two more weeks to resign before the PSA takes matters into its own hands.
Mrs 'Amanaki says the PSA spoke to the new Minister of Finance and National Planning, 'Aisake Eke, who agreed the payment was unlawful.
But she says Mr Eke has not taken any action.