Kallon made his position known in a statement by Eve Sabbagh, the Head, Public Information, UN Office for Coordination of Humanitarian Affairs (OCHA) on Thursday in Maiduguri.
The three aid workers were abducted while travelling along the Maiduguri-Monguno Road on Dec. 22, 2019.
The aid workers and some other captives were freed on Wednesday by their captors.
Kallon said that the UN and the humanitarian community were happy with the development, and expressed the hope that two other aid workers still in captivity would be released soon.
He said “I am deeply relieved that some civilians, including three aid workers who were abducted by non-state armed groups along the Maiduguri-Monguno Road on Dec. 22, have been released.
“The humanitarian community in Nigeria shares the joy of the families, friends and colleagues of these aid workers,” he said.
The UN official described the aid workers as highly dedicated humanitarians working to provide life-saving support to Nigerians affected by the crisis in the North-East.
He expressed worries that such category of persons were targeted for abduction by gunmen.
Kallon also expressed concern over the fate of Grace Taku, abducted in July 2019 and Alice Loksha, who was abducted in March 2018.
“Grace Taku was abducted near Damasak in July 2019, while Alice Loksha, a nurse and a mother was abducted during an attack in Rann in March 2018.
“They are still held captive by non-state armed groups, the UN and its humanitarian partners call for their immediate and safe release,” he said.
He further expressed worries over the increasing level of insecurity being faced by aid workers who were providing urgent and vital assistance to civilians affected by the crisis.
He disclosed that a total of 12 aid workers died in 2019, saying “this is twice the number of deaths in 2018.
“The humanitarian community is troubled by the increased trend in vehicular checkpoints set up by non-state armed groups along main supply routes in Borno and Yobe states.
“These checkpoints expose civilians and humanitarians to heightened risks of being killed or abducted.
“Parties to the conflict should work toward protecting civilians and aid workers from grave violations of international laws,” he said.