A Swiss-based mine-clearing organisation has suspended operations in southern Sudan after two of its clearance experts were killed in an ambush.
The Swiss Foundation for Mine Action (FSD) said it did not know who was behind the attack earlier this week on a convoy of workers.
The FSD said that a mine clearance team working for the United Nations World Food Programme's road reconstruction and rehabilitation programme was ambushed on Monday. The workers had been on their way to their base camp near Juba.
Two mine clearers – an Iraqi and a Sudanese who have both now been named – were killed and two government soldiers accompanying the convoy were injured, said the FSD.
"We've for the time being suspended all work on that particular stretch of road where we had been doing clearance operations," Ian Clarke, the FSD's director of operations, told swissinfo. The suspension started on Tuesday.
He added that three teams at other locations in southern Sudan had also been pulled back into their camps while the FSD evaluated whether to allow work to continue. There is no blanket suspension on their activities, but they are currently not allowed to travel long distances.
Clarke said on Wednesday that the FSD was concentrating its efforts on repatriating the bodies of the two victims who were the clearance team's supervisor and leader. He said that the FSD was in close contact with the workers' families.
The foundation, which also carries out work in Bosnia, Iraq and Afghanistan, said that the deaths had come as a shock.
"We were founded in 1997 and although the work of demining is relatively dangerous, it's the first time we've ever had fatalities within the organisation," said Clarke.
Clarke said the next step would be to carry out an investigation into the incident, for which the FSD hoped to receive the help of the Sudanese authorities and the international community.
Both the UN and the Swiss government, which contributes up to ten per cent of the FSD's budget, were quick to condemn the ambush.
Speaking from the Sudanese capital Khartoum, the UN's top envoy for Sudan, Jan Pronk, called it a "cowardly attack".
In a statement released on Tuesday, the Swiss foreign ministry said that the ambush "puts into doubt the assistance of the international community as a whole and therefore endangers the reconstruction in southern Sudan".
The statement called on the Sudanese authorities to do everything in their power to improve the long-term security situation and guarantee the safety of humanitarian workers.
The FSD said on Wednesday that it was not prepared to speculate on who was behind the killings. However, it has been reported that the UN suspects rebels from the Ugandan Lord's Resistance Army (LRA).
The Geneva-based FSD deploys 30 expatriates and 250 locals in the Sudan mine-clearance programme, which aims to make safe three main access routes from the south into Juba.
Southern rebels signed a peace agreement with the Khartoum government in January to end more than two decades of civil war. While the south was not heavily mined, the terrain and lack of maps have made locating mines very difficult.
swissinfo, Isobel Leybold-Johnson
Swiss Foundation for Mine Action was founded in 1997 and in based in Geneva.
It is a non-governmental organisation specialising in mine education and clearance activities.
It has conducted mine action operations in many countries, including Bosnia, Afghanistan and Iraq.
The FSD has been in Sudan since 2003, supporting humanitarian aid programmes in the country.