The director of Tonga's national centre for women and children, Ofa Guttenbeil Likiliki, says she is disgusted and gravely concerned about the government's lack of commitment to creating a legal system that supports women's rights.
The Tongan assembly this week voted not to ratify CEDAW - the UN Convention on the Elimination of All Forms of Discrimination Against Women.
Ofa Guttenbeil Likiliki says the cabinet has made the decision based on misinformation.
She says discrepancies between international obligations and domestic laws can be worked through by the government.
She says Tonga is one of only a few countries not to ratify CEDAW.
"Tonga is part of the five per cent of those who have not ratified, and that is alongside countries such as Iran, Sudan, Somalia and in the Pacific, Nauru and Palau. We are disgusted at the decision made, and we are not going to put down our struggle to get this convention ratified."
Ms Guttenbeil Likiliki says women's groups in Tonga are not ready to give up the fight for equal rights and are likely to petition the government and they may also write a letter seeking support from the Princess Regent of Tonga.