Juba, South Sudan (CNN) -- Sudan has withdrawn its soldiers from Abyei, a disputed border region also claimed by South Sudan, but has left police officers, the United Nations peacekeeping mission said Wednesday.
"The mission has confirmed the full withdrawal of the SAF from Abyei area yesterday," said Josephine Guerrero, a spokeswoman for the U.N.'s Department of Peacekeeping Operations in New York, referring to the Sudan Armed Forces. "Armed police forces are still in the area."
South Sudan's army spokesman, Philip Aguer, said he is "skeptical" that Sudan has truly pulled troops out.
He said he had received reports that the Sudan Armed Forces left two platoons of soldiers dressed in police uniforms in Abyei town, and that two battalions remain about 40 miles away in Diffra, which is the only oil field inside the disputed territory.
"We have our reservations about Sudan's claims that it withdrew from Abyei," he said, adding that his government is investigating reports that Sudanese soldiers remain in the area.
The conflicting claims come on the second day of renewed peace talks between Sudan and South Sudan, which are being hosted by the African Union in the Ethiopian capital of Addis Ababa.
Talks have been ongoing since the South declared independence on July 9 of last year, but Sudan pulled out of negotiations last month as border clashes brought the countries to the brink of war.
A U.N. Security Council resolution adopted this month threatened sanctions if the countries refused to cease hostilities and return to talks.
South Sudan complied with the Security Council's demand that it withdraw forces from the contested, oil-rich area of Heglig, as well as police it had stationed in Abyei. The resolution also required Sudan to withdraw its forces from Abyei.
The United Nations and the African Union have made repeated requests that Sudan withdraw troops after it invaded Abyei a year ago. More than 100,000 people remain displaced, according to the World Food Program, which is supporting the displaced community in the South Sudanese town of Agok.
Under a 2005 peace agreement that ended Sudan's two-decade civil war, Abyei residents were to take part in a referendum on whether to join the South or remain a special administrative region within Sudan. The vote was to take place in January 2011, at the same time as the referendum that led to South Sudan's secession. But disputes over who was eligible to vote prevented the referendum from going forward in Abyei.
In a 2009 ruling, the Permanent Court of Arbitration in The Hague placed Abyei's boundaries around the traditional homeland of the Ngok Dinka tribe. Those borders excluded most of the oil fields in the area as well as the members of the Misseriya tribe, who often receive support from Khartoum, Sudan's capital. The nomads spend part of the year grazing their cattle in Abyei and said they should also be able to vote.
The U.N. Security Council and the African Union have given Sudan and South Sudan three months to resolve post-secession issues, including the fate of Abyei. Other points of contention are citizenship for people from both countries who now find themselves living in either country, border demarcation and oil revenue sharing.
With independence, South Sudan acquired three-quarters of the formerly united country's oil reserves. But the new nation depends on pipelines and processing facilities that remain in Sudan.
Negotiators have failed to agree on how much the landlocked South should pay to use those facilities. South Sudan halted oil production in late January after accusing Sudan of stealing $815 million worth of its crude. Sudan said it had confiscated the oil to make up for unpaid fees.