Darfur rebels have launched a brazen attack on the Sudanese capital for the first time in their five-year insurgency, in a show of force that revealed the government’s vulnerability and raised tensions in the region.

The rebels clashed with government troops in Omdurman, Khartoum’s twin city across the Nile, on Saturday, after making a lightning advance across 600km of desert and bush in a convoy of between 100 and 200 vehicles.