The UN World Food Programme (WFP) has condemned an armed attack on its boat convoy transporting food assistance around Shambe North area in South Sudan.

Matthew Hollingworth, WFP Country Director, said the boat convoy consisted of three cargo vessels and one speed-boat that were carrying food assistance from Bor to Melut and Malakal before being attacked around Shambe North. 

"The three cargo vessels had food items as well as 13 crew members on board. One person is missing and presumed killed, while three suffered gunshot injuries," said Hollingworth in a statement issued in Juba on Wednesday.  

"WFP condemns in the strongest terms any attack on humanitarian workers and contractors, who risk their lives delivering much-needed food assistance to the most vulnerable people," Hollingworth added.

It called on all parties in the youngest nation, which is seeking recovery from more than seven years of conflict to allow unimpeded humanitarian access, respect for international law and conditions that allow humanitarian workers to carry out their jobs in safety. 

"Our thoughts are with the families of the missing crew member, and we wish a speedy recovery to those who suffered injuries," said Hollingworth. 

He urged the South Sudanese authorities to hold accountable those behind the latest violence.

The WFP official said the food assistance was intended for people displaced who have lost their homes and their crops as a result of the floods.

"Over 800,000 people have been affected by the floods in South Sudan, on top of many months of subnational violence, and years of conflict that have ravaged people's homes and caused widespread hunger and malnutrition," it noted.

It added that WFP plans to reach five million people with food and nutrition activities using air, road and river to deliver vital food to isolated communities in the most remote parts of the country.

South Sudan is ranked among the worst countries globally for humanitarian workers to operate. Since the outbreak of conflict in December 2013, over 120 aid workers have been killed in the line of duty.