Sudan (Creative Commons)

The state of emergency covers cities in the provinces of South Kordofan, White Nile and Sinnar, which are on the eastern half of Sudan's border with the breakaway republic, al-Bashir said. Disputes over demarcating the border and dividing oil revenue have brought the two sides to the brink of war, according to the Associated Press.

A journalist in South Sudan reported coming under attack by Sudanese helicopter gunships and MiG fighter jets Sunday morning. Robyn Kriel told CNN she was traveling to the front line with the Sudan People's Liberation Army of South Sudan when heavy gunfire forced them to take cover in trenches dug by the army.

Tension escalated this month when South Sudan occupied the north's main Heglig oil field for 10 days, Agence France Presse reported. Heglig oil facilities are vital to the economies of both nations, accounting for about half of Sudan's production of 115,000 barrels a day.

Sudan arrested three foreigners on Saturday in a disputed area on the border with South Sudan, claiming that they had military hardcore and an armored vehicle, according to the AP. But a representative for one of the detained said they were on a humanitarian mine-clearing mission.

South Sudan separated last July after a peace deal ended a long-running civil war. The war resulted in the deaths of 2 million people and a peace agreement that included an independence referendum for the southern portion of Sudan.

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