Pro-Russian insurgents in Ukraine's eastern separatist Donetsk region say they have banned Doctors Without Borders (MSF) from working in the area for alleged espionage activity and other crimes.
Medics with the Nobel Peace Prize winning organisation were kicked out of the war-torn province along with nine other Western aid groups for unspecified reasons this week.
But the official news site of the self-proclaimed Donetsk People's Republic on Sunday said MSF had been expelled for "espionage" and other subversive behaviour.
The Geneva-based relief group "collected our defence data and also conducted psychological training in frontline regions that seriously confused the locals," the separatist website said.
MSF director of operations Bart Janssens warned that the ban would have an impact on public health and said the group had asked the Donetsk authorities to reconsider.
"We are extremely worried. MSF is the largest player in the region and now we will have to stop people's treatment," Janssens told AFP by telephone.
"This is a dramatic decision," he said.
Donetsk insurgents on Friday also closed the field hospitals of UN agencies such as the World Food Programme.
But they spared the International Committee of the Red Cross and the Czech Republic's People in Need - two other earlier targets of investigations.