The Security Council made the decision on Wednesday following repeated demands by UN Secretary-General Ban Ki-moon.
The number of the UN Interim Security Force for Abyei (UNISFA) will increase to 5,326 troops from the current 4,200. All the soldiers will be sent to the region from Ethiopia.
In a recent report to the Security Council, Ban said that rival groups in Abyei “remain armed, hostile and highly distrustful of each other.”
He said extra forces are necessary for securing Abyei’s borders in the face of growing presence of armed groups.
The tensions in Abyei, a region claimed by South Sudan and Sudan, intensified earlier this month after Kual Deng Majok, the Abyei leader of the Dinka Ngok, and an Ethiopian UN peacekeeper were killed. Both Juba and Khartoum slammed the deadly clashes.
Despite necessary measures taken by South Sudan and Sudan in order to settle their differences since March, Abyei’s status is not yet determined.
In July 2011, South Sudan voted to break away from Sudan following a two-decade civil war that killed about two million people in the East African country. But the new oil-rich nation, which is one of the least-developed countries in the world, has had to confront ethnic tensions and rebellions of its own.