Attacks on aid workers delivering supplies in Somalia have increased this year with some resulting in deaths of staff, a senior UN humanitarian official said on Friday.

Humanitarian Coordinator for Somalia Peter de Clercq said more than 100 incidents targeting humanitarian workers had been reported thus far this year, and four of them had been killed.

"In Somalia, health and aid workers, who work and care for people affected by violence are being targeted. Medicine and relief supplies are looted," de Clercq said during an event to mark World Humanitarian Day in Mogadishu.

"Humanitarian workers are detained or denied access to people in desperate need. This is unacceptable," he added in a statement released after the event.

He thanked aid workers for risking their lives on a daily basis to save the lives of others in distress. "We salute and thank aid workers for their bravery and unwavering commitment, in particular those on the frontline, closest to those in need, saving lives and protecting livelihoods," he said.

"It's through their commitment that famine has been averted in Somalia. They are our daily inspiration," de Clercq noted.

The UN relief official noted that humanitarian workers had not only suffered death, injuries and abductions, but also expulsion from the country in the course of fulfilling their duties.

Somalia's Permanent Secretary in the Ministry of Disaster Management and Humanitarian Affairs, Mohamed Moalim, promised that the government will offer protection to humanitarian workers as well as needy civilians.

"The government will also do its utmost to protect not only civilians, but also aid workers who continue to risk their lives to save others," Moalim said.

World Humanitarian Day is observed every year on Aug. 19 to pay tribute to aid workers who risk their lives in humanitarian service, and to rally support for people affected by crises around the world.