Chad has shut its border with Sudan, hoping to reassert its neutrality in the devastating conflict.

Chad's government officially maintains it is neutral in the three-year-old battle between Sudan's paramilitary Rapid Support Forces (RSF) and the regular army that has left tens of thousands dead and forced more than 12 million from their homes, according to the United Nations.

Nearly one million of the displaced are in Chad, however.

Darfur, a vast region in western Sudan bordering Chad, is almost entirely under RSF control since the city of Al Fasher fell in October.

RSF attacks near Chad border

On February 21, the RSF claimed to have captured the border town of Al Tina, the twin of Al Tine on the Chadian side.

The paramilitaries have conducted several operations near the Chad border, killing 15 Chadian soldiers and eight civilians since December, according to an AFP count.

Chad shut the border on February 23 in a move that Communications Minister Gassim Cherif Mahamat said aimed to prevent "any risk of the conflict spreading."

Chad "reserved the right to retaliate against any aggression or violation of the inviolability of its territory and its borders", he added.

Stance of neutrality

While cross-frontier trade and movement is halted, some special exemptions are planned so that Sudanese can still seek refuge in Chad, the communications minister said.

The 1,400-kilometre desert border is hard to control.

But the announced closure allows the Chadian authorities to regain a stance of neutrality "faced with RSF allies who are losing ground militarily", a Chadian diplomat told AFP speaking on condition of anonymity.

The UN rights office last month accused Sudan's paramilitaries of war crimes and possible crimes against humanity during the capture of Al Fasher, saying some 6,000 people were killed in just three days.