Sudan's official state news agency SUNA said on Sunday that President Omar al-Bashir had introduced a state of emergency in the regions bordering South Sudan.

The measure affects the regions of South Kordofan, White Nile and Sennar. It suspends the constitution, gives authorities wider powers of arrest and formally imposes a trade embargo against the South that has been in place unofficially since the country gained independence last July after a referendum.

The two uneasy neighbors have been at odds ever since South Sudan's formation, but fighting over the disputed Heglig oilfields - occupied by the South for several days earlier in April - and reports of Sudanese airstrikes on southern territory have raised the stakes in recent weeks.

The divide of the country was designed to bring a halt to ethnic violence after a 22-year civil war in which an estimated 2 million people died. Sudan and South Sudan have so far failed to agree, however, on issues including border demarcation, the division of oil revenues and other resources.

During the South's occupation of the Heglig oil fields, al-Bashir said Sudan would crush the South's "insect" government, while Southern President Salva Kiir said on a recent visit to China that attacks on his territory amounted to a declaration of war from the government in Khartoum.

Foreigners still in Sudanese custody

The Sudanese military announced on Saturday that it had arrested four people - one Briton, a Norwegian, a South African and a South Sudanese national - saying they were captured in the disputed Heglig region.

Colonel Sawarmy Khaled said on state television that they were carrying out military activities and had military equipment.

A representative of the Norwegian People's Aid (NPA) organization said one of the men arrested was former soldier John Sörbo, describing him as "one of our most experienced aid workers" and saying he was on a mine-clearing mission. The NPA said Sörbo had worked on demining missions in the region for the past seven years.

Norway's ambassador to Sudan, Jens-Petter Kjemprud, said his government had not yet been permitted to speak with Sörbo.

"We have still got no access," Kjemprud told the AFP news agency. "We are concerned and would like to see these citizens as soon as possible.

A British embassy spokeswoman said her mission had also requested consular access and was "urgently investigating the arrest of a British national in Sudan."

A South African demining company, meanwhile, said that the four people were working on a UN mine clearance mission, also saying that the arrested Briton was a UN employee - apparently corroborating an initial UN statement on Saturday that one of the quartet arrested was thought to work for the UN.

msh/ccp (AFP, AP, Reuters)