Sudan has threatened to close its border with South Sudan in the coming days if its neighbour fails to expel the insurgent groups. South Sudan, which gained independence from Sudan in 2011, promised to expel the militants groups battling Khartoum within three weeks.
Sudan has often accused South Sudan of supporting insurgents in the regions that run along its border in the south: Darfur, Blue Nile and South Kordofan.
Since South Sudan split from Sudan ending a two decade-old civil war, both countries have accused each other of backing rebels on their respective territories.
The border between the former rivals remained closed after the split, and was re-opened after four years in January 2015. Traders and pastoralists used to regularly cross the frontier.
According to local broadcaster, eNews Channel Africa, (eNCA), Kamal Ismail, Sudan's minister of state in the foreign ministry said South Sudan's Vice President Taban Deng had vowed to expel the rebels within 21 days during his visit to Khartoum in August. It was his first trip to Khartoum after replacing former rebel leader Riek Machar, during which he held talks on mutual issues.
"If the government of South Sudan fails to fulfil this commitment, then the government of Sudan will close the border and also stop sending humanitarian aid to South Sudan," he said. "South Sudan must take a political decision to expel these rebel groups."
Relations between the two countries have remained strained since the north-south split with the border, especially the district of Abyei, a constant source of friction. The frontier is used by refugees fleeing the conflict in Juba.
The United Nations refugee agency recently said Khartoum hosts more than 247,000 South Sudanese refugees. South Sudan joined countries like Syria, Afghanistan and Somalia in crossing the one-million mark on refugees fleeing the world's youngest nation since renewed clashes in July.