A forest fire in Nicaragua that has been burning out of control for a week has blackened almost 9,000 acres (3,585 hectares) in a southern nature reserve.

The Indio Maiz reserve is on Nicaragua's border with Costa Rica, but the Nicaraguan government has refused Costa Rican offers of aid. The two countries have had long-running disputes over other areas of their border.

Costa Rica's firefighting force said Monday that it was told by Nicaraguan officials that soldiers are being sent to fight the blaze so no Costa Rican help was needed.

Nicaragua says it has 800 soldiers, five planes and 10 boats fighting the fire.