The President in Kiribati says his Government would only move its residents to Fiji as a last resort.
President Anote Tong's cabinet has been discussing buying the about 2200 hectare Natoavatu Estate in Vanua Levu.
The Associated Press has suggested the entire population of Kiribati could be moved to Fiji if the sea around the republic continues to rise.
A real estate website says the estate is the largest block of land for sale in Fiji which could be used to build a resort or for farming.
Mr Tong says the purchase would be for investment purposes only.
He says the purchase would be to enhance the country's economic and social resilience to the effects of climate change.
Mr Tong says relocation is a last resort.
A spokesperson says the cabinet is expected to agree to buy the land this week, but he says the plan would also have to be passed by parliament before it goes ahead.
Earlier opposition MP and former president, Teburoro Tito, ridiculed the move, saying parliament had not discussed any such action by the government.