The United Nations Security Council is demanding Sudan withdraw its troops from the disputed region of Abyei and that it reach an agreement with South Sudan on the status of the oil-rich border region.

The council on Thursday extended the U.N. security force mission in Abyei for six months. It also expressed concern at delays in forming a jointly-run administration and police force for the area.

The 15-member body welcomed last week's withdrawal of hundreds of South Sudanese forces from Abyei, saying Sudan should follow suit “immediately and without preconditions.”

But Sudan's deputy U.N. ambassador, Idris Ismail Faragalla Hassan, said South Sudan had taken the wrong approach. He said both sides should withdraw at the same time under the supervision of an international body.

“This withdrawal should take place simultaneously and it should be monitored by a body agreed upon by the two parties. The body will be composed of the two parties as well as the African Union. What happened is that the government of South Sudan took a piecemeal approach, not the comprehensive approach that the government of Sudan is calling for.”

The Security Council earlier this month threatened sanctions against the two Sudans if they do not cease fighting and return to negotiations. Although violence has lessened in the past week, the nations failed to meet a Wednesday deadline to resume talks.

Rising tensions have pushed the countries to the brink of war, just 10 months after South Sudan formally split from the north.

The countries have yet to resolve critical issues from their split, including citizenship questions and disputes over oil revenue and borders. The neighboring countries have accepted “in principle” an African Union roadmap for an end to the fighting.

The fighting has displaced tens of thousands of people along the two countries' border area, creating a humanitarian crisis that aid agencies say is rapidly growing worse.