JUBA, July 5 (Xinhua) -- The UN Children's Fund (UNICEF) on Thursday condemned the killing of one of its drivers by unknown gunmen along the Juba-Bor road in South Sudan.

James Aldworth, the UNICEF South Sudan spokesperson, said two of their trucks came under attack on Wednesday morning resulting in the death of one of the drivers.

"We can confirm that yesterday (Wednesday) morning two trucks carrying UNICEF education supplies were attacked by armed men as they travelled along the Juba-Bor road. One person, an assistant driver, was killed," Aldworth told Xinhua.

He disclosed the latest killing brings to nine the number of humanitarian workers killed this year alone and 107 since the outbreak of the December 2013 conflict in South Sudan.

"We strongly condemn this senseless assault directed against civilians working to deliver humanitarian supplies to those in need, in trucks that were clearly marked with the UNICEF insignia. Given the circumstances, the loss of the driver will be recorded as an aid worker death, the ninth so far this year and the 107th since this conflict began in 2013," he revealed.

This latest killing comes after President Salva Kiir and rebel leader Riek Machar declared last week permanent ceasefire and also promised to grant unlimited humanitarian access after they attended talks in Khartoum mediated by the Sudanese President Omar Al-Bashir as part of efforts by the East African bloc, IGAD to end the more than four years of conflict.