The volunteer, Samuel Sargbah, was shot dead on Saturday at about 21:00 hrs local time by an unknown assailant while sitting in his car in Rwanda's capital Kigali.
"I am deeply shocked and saddened by the senseless murder of yet another humanitarian worker," said Bertini, urging for a thorough investigation and the bringing to justice of the murderer.
Bertini said that Sargbah, a Liberian national, was a dedicated and hard-working professional.
Bertini called on the international community to take concrete steps to ensure the safety of humanitarian workers and put a stop to attacks and killings of aid workers.
Sargbah is the third WFP worker killed in Rwanda in last three years. In the past ten years, 59 WFP employees have been murdered or died in the course of carrying out their duties.
WFP is the United Nations' front-line agency in the fight against global hunger. Last year, its relief workers fed 88 million people, including most of the world's refugees. Headquartered in Rome, Italy, WFP has food aid operations in 82 countries.
For more information please contact:
Trevor Rowe, WFP/Rome -Tel. +39-6 6513-2971, Cell: 0039-(0)348-6099-463
Francis Mwanza, WFP/Rome -Tel. +254-2-622336, Cell: 0039-(0)348-6099-490