The aid agency Medecins Sans Frontieres (MSF), has expressed shock at the killing of one of its local staff in Sudan's war-torn Darfur region.
Aid workers are increasingly at risk in Darfur
The aid worker was shot in front of its warehouse in an attack on Labado last week, a spokesman confirmed.
MSF says it will continue its presence in Darfur, but called for aid workers' neutrality to be respected.
On Tuesday, UK charity Save the Children withdrew from Darfur after four of their staff were killed.
UN Secretary-General Kofi Annan has expressed deep concern at the deteriorating security situation in Darfur and called on the government and rebels, who have adjourned peace talks until January, to cease their attacks.
The UN has termed Darfur one of the world's worst humanitarian crises, with some two million refugees relying on aid handouts.
MSF's Ton Koene said 29 other staff, who worked at its feeding centre and clinic in Labado, were caught up in the fighting and were unaccounted for.
They are believed to have fled the area following the attack which has displaced some 30,000 people, he said.
"I have honestly no idea where they are, whether they are ok or not," Mr Koene told the BBC's Focus on Africa programme.
Eyewitnesses - who had escaped the attack on Friday last week by what they described as Arab militia - said Labado is now empty and destroyed, he said.
This is the second Sudanese MSF aid worker to have been killed over the last three months.
But Mr Koene believed that in the case of MSF the relief workers were not being deliberately targeted.
"Any Darfuri is at risk in Darfur," he said.
Tens of thousands of people have been killed in almost two years of clashes between rebels, the army and Arab militia groups.
On Tuesday, Save the Children's director Mike Aaronson called for a stop to "foot-dragging" by the UN Security Council and for more African Union (AU) troops to be committed to the ground.
The 1,000 AU troops are having little impact on the fighting in Darfur, but Said Jinnitt, head of the African Union's peace and security council, says this will not continue.
"The African Union is determined to take a very firm stand against the parties who violate the ceasefire agreement, on the one hand; secondly we need to have some measure against whoever violates."
According to BBC African analyst Martin Plaut, if the AU allows the crisis to continue unchecked it will find its status eroded and dismissed as little more than a talking shop.
"The deployment of the African Union troops and police needs to be speeded up," Mr Annan told reporters on Tuesday evening.
The AU force currently stands at less than a quarter of the projected number of 4,000 troops.
Mr Annan warned the Security Council would consider a full range of options if fighting does not stop.
There are two existing UN resolutions threatening possible sanctions against the Sudanese authorities.
Mr Annan also urged the Sudanese government and southern rebels to sign their comprehensive peace settlement before the 31 December deadline to "promote peace throughout the country".