Residents of the city reported heavy bombing of the area but the army has denied the RSF's claim that it has destroyed the palace.

The paramilitaries said they would reply decisively.

The old Republican Palace is located along the Blue Nile River, near the current premises that were inaugurated in January 2015.

The two warring parties have been holding peace talks in Saudi Arabia but there is little sign of progress.

Conditions for civilians trapped in the city continue to deteriorate, with doctors saying the health service is near total collapse.