Sudan declared a state of emergency on Sunday along its border with South Sudan that has been at the centre of a worsening border dispute.
President Omar al-Bashir's announcement in Khartoum marks the latest increase in tension just months after the oil-rich south gained independence from its northern neighbour.
Southern Sudan reported yesterday that two days of fighting with a militia backed by Sudan in the oil-producing Upper Nile state had left 21 dead.
The local state of emergency in the north also followed the capture by Sudanese forces of a British citizen, Norwegian, South African and a South Sudanese in the contested Heglig area.
Sudanese army spokesman Colonel Sawarmi Khalid Saad claimed on TV that the four had military backgrounds.
But the Norwegian People's Aid NGO said that one of those captured was John Soerboe, who was deployed on a mine-clearing project.
The organisation described Mr Soerboe as "one of our most experienced aid workers" who had been working clearing mines in the region since 2005.
South Sudan reported on Saturday that it has secured an unconditional loan from China to fund new infrastructure.
Information Minister Barnaba Marial Benjamin said that the money will finance agriculture, transport, telecommunications and hydropower projects.
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