The president of Kiribati has described members of the new political party, Kiribati First, as traitors.
Taneti Maamau told Parliament that the MPs left the government without discussing their grievances with caucus.
Thirteen MPs have joined Kiribati First, creating a minority government that holds just 20 of the 46 seats in Parliament.
The new party was set up by the ruling party's former chair, Banuera Berina, after the government switched allegiance from Taiwan to China in September.
A member of Kiribati First told RNZ Pacific's correspondent that MPs were not consulted by the government before it made the switch.
President Taneti Maamau told Parliament that he was surprised by the MPs' departure but he respected their decision.
Three government bills were defeated in Parliamentary votes yesterday, fueling speculation the opposition could call for fresh elections.