Former rebels in southern Sudan on Tuesday agreed to rejoin the national government, even though the most contentious issue between them has yet to be resolved.

The former rebels, who quit the government in protest against Khartoum’s refusal to implement a peace deal, and the ruling National Congress party said they still had not resolved a key issue in their long confrontation: the demarcation of the north-south border that cuts through the oil-rich Abyei region.