(CNN) -- The governments of Sudan and South Sudan have reached an agreement that will allow the withdrawal of their troops from the disputed border region of Abyei, according to United Nations officials.
Special Representative to the Secretary-General Edmond Mulet told reporters Thursday that the agreement was reached in Addis Ababa, Ethiopia.
"There are encouraging signs," said British Ambassador Mark Llyal Grant, "beginning with the withdrawals of SAF and SPLA forces and establishment of South Sudan's government. But we are deeply concerned on a range of issues, 600 deaths in South Sudan, obstacles in Abyei, serious humanitarian situation in South Sudan."
More than 1,500 Ethiopian troops have been deployed in Abyei since June, when the Security Council voted to establish UNISFA after north-south violence resulted in more than 100,000 people fleeing their homes.
Abyei is a region under dispute between Sudan and the newly formed country of South Sudan, and was a battleground for decades in the brutal civil war fought between northern and southern forces. A referendum on whether the area should be part of the north or the South has been delayed over disagreement over who is eligible to vote.
The region, the size of Connecticut, is home to the Ngok Dinka people, who are closely allied with the South, but the area also serves as grazing grounds for northern Misseriya tribes.
Meantime, the Global Centre for the Responsibility to Protect says the U.N. Security Council is failing to protect the people of South Kordofan, Sudan. The group says they have seen a pattern of abuses in the region over the past four months, claiming that individuals are targeted because of ethnicity or political affiliation and that humanitarian agencies are being denied access to those in need of help.
"Sudan is already the site of no less than three UN peacekeeping missions." said Dr. Simon Adams, Executive Director of the Global Centre for the Responsibility to Protect. "Now is the time to step back and reflect on the nature of the regime in Khartoum and its hand in the ongoing direction of mass atrocity crimes. The U.N. Security Council needs to speak strongly and with one voice. The situation in South Kordofan and now also Blue Nile must not be allowed to fester. Perpetrators want silence, victims need action."
Last month, Amnesty International and Human Rights Watch released reports that said Sudanese government airstrikes in the Nuba Mountain area had killed at least 26 people and have forced more than 150,000 people from their homes in South Kordofan state. At least 26 people have died and dozens wounded in the airstrikes, the rights groups said.
The researchers, who were on the ground, witnessed some of the attacks, according to the rights groups.
"Antonov aircraft dropped bombs over farmlands and villages on a near-daily basis while researchers were on the ground from August 14-21," Amnesty said.
Aid groups, including the United Nations, have warned that South Kordofan state is at risk of high levels of malnutrition and mortality because the government has restricted access to the area.
In the past, the Sudanese government has said rebels are to blame for the violence in the region, and has been engaged in a fierce campaign to battle what it says are militia in the area.
Nuba fighters helped South Sudan during the civil war with Sudan, which raged for decades and left millions dead.
South Sudan became an independent nation in July. South Kordofan remains a territory of the Sudanese government in the north, but it borders South Sudan.