N'djamena — Chad has officially closed its border with Sudan, saying the move is aimed at preventing the three-year conflict in its eastern neighbour from spilling into its territory, authorities said.

The government said it continues to maintain a neutral stance in the war between Sudan's army and the paramilitary Rapid Support Forces (RSF), which has devastated large parts of the country.

The conflict has caused widespread destruction, killing thousands and forcing more than 12 million people from their homes, according to the United Nations. Nearly one million of those displaced have sought refuge in neighbouring Chad.

Much of Sudan's vast western region of Darfur, which borders Chad, has fallen under the control of the RSF after the group seized the city of Al Fasher in October.

On February 21, the RSF said it had taken control of the border town of Al Tina, which lies opposite the Chadian town of Al Tine.

Clashes and cross-border attacks near the frontier since December have killed 15 Chadian soldiers and eight civilians, authorities said.

Chad formally shut the border on February 23, with government spokesman and Information Minister Gassim Cherif Mahamat saying the decision was intended to prevent "any risk of the conflict spreading".

He added that Chad reserved the right to respond to any attack or violation of its territory or borders.