John Sørbø was one of four foreigners arrested in the Heglig oilfield area of southern Sudan last week. The aid workers were assessing the impact of recent fighting between Sudan and South Sudan.
The British embassy said on Tuesday it had met with one of its citizens allegedly detained by Sudan's army along the tense southern border and confirmed that he was is in good condition. Chris Fielding has been held for at least three days along with Sørbø, South African Thabo Siave and an unidentified South Sudanese.
Sudan's army said on Saturday it arrested them in the Heglig oil region as they collected "war debris for investigation," and suggested the men were working in support of South Sudan in its "aggression" against the north.
Their employers say they were on a demining mission on the South Sudanese side of the border.
Diplomats said they had been pushing for access to the captives, who are being held at a military facility in Khartoum.
"We had consular access and he is in good health," a British embassy spokesperson told AFP.
Norwegian Ambassador Jens-Petter Kjemprud said he was still waiting for a meeting with Sørbø, but has been told that the captive's health is good.
Jan Ledang, country director for the Norwegian People's Aid mission in South Sudan, identified Sørbø as one of his employees.
A South African demining company said two of its workers were among the group abducted by the Sudanese military while on a UN landmine clearance contract in South Sudan.
The ambassadors of Norway, Britain and South Africa met on Monday with a senior foreign ministry official, ministry spokesman Al-Obeid Meruh said in a statement.
He said the ambassadors were told their citizens are under investigation because they illegally crossed the border into a military area, and had military equipment with them.
Nationalist feeling has intensified in Sudan after South Sudan seized and occupied the north's main Heglig oilfield for 10 days, a move that coincided with Sudanese air strikes against the South.
It was the most serious fighting since the South's independence last July, and raised fears of a wider war.
Sudan declared on April 20th that its troops had forced the Southern soldiers out of Heglig, but the South said it withdrew of its own accord in line with international calls.