(VOVworld) - Rebels in South Sudan have abducted 12 UN contractors operating a barge carrying fuel, weapons, and equipment for international peacekeepers.

Rebel soldiers guard the village of Majieng in South Sudan on September 20, 2014. (Archive photo: AP)

UN spokesman, Stephane Dujarric, said on Thursday that the incident happened in the town of Kaka, in the northeastern province of Upper Nile.

Dujarric demanded that the “contractors be released immediately, unharmed, and unhurt,” adding that attacks against peacekeepers may constitute a war crime.

In a similar incident on Monday, 100 heavily-armed rebels kidnapped 20 peacekeepers when they captured a barge traveling on the Nile, north of Malakal. Those peacekeepers were released on Thursday.