A South Sudanese military official says 11 Sudanese traders were killed earlier this week by unknown gunmen as they crossed into South Sudanese territory.

South Sudan military spokesman Col. Philip Aguer said Friday that "gangsters" ambushed three trucks at a trading center near the border town of Renk on Wednesday morning. He says the bodies were later discovered by another group of traveling traders.

The incident happened nearly two weeks after South Sudan and Sudan agreed to open 10 crossing points along their border to boost the movement of goods and people between the two countries.

Aguer blamed the attack on militiamen operating inside Sudan who don't want peace to prevail between the Sudans, which have had moments of border tension since the south declared independence in 2011.