* South says troops remain in region, dressed as police
* Disputed Abyei area is a major source of tension
* Talks will be first since fighting stopped
* Sudan announced withdrawal before negotiations began (Adds details, reaction from South Sudan)
KHARTOUM/ADDIS ABABA, May 30 (Reuters) - Sudan's army has withdrawn from the disputed region of Abyei bordering South Sudan, the United Nations confirmed on Wednesday, removing an obstacle to talks between the neighbours to end hostilities.
But in a sign tensions were still running high, South Sudan accused its northern neighbour of keeping dozens of troops in the region dressed as police. Both sides have accused each other before of violating troop deployment agreements in Abyei.
Sudan seized Abyei a year ago after an attack on a military convoy, blamed by the United Nations on southern forces, and came close to all-out war last month when border fighting escalated in the worst violence since South Sudan's secession.
"The (U.N.) Secretary-General (Ban Ki-moon) welcomes the full withdrawal of the Sudan Armed Forces from the Abyei area...He calls on the Government of Sudan to withdraw all remaining armed police forces," an emailed U.N. statement said.
South Sudan had already withdrawn its troops from Abyei, which has fertile grazing lands and extensive oil reserves - a major sticking point in negotiations after the split in July under a 2005 agreement that ended decades of civil war.
Sudan still has a police force of about 50 inside Abyei, a diplomat close to peace talks told Reuters, and they were expected leave soon.
Another official said South Sudan has also kept more than 20 unarmed security personnel in the disputed area.
South Sudan's Information Minister Barnaba Marial Benjamin accused Sudan of keeping several platoons of soldiers in the region under the guise of police officers.
"Sudan Armed Forces (SAF) have redeployed and not completely withdrawn completely from Abyei," he told reporters in Juba.
"The Republic of South Sudan insists that SAF must withdraw its so-called police from Abyei, and must stop escalating aggression against the Republic of South Sudan."
No official comment was immediately available from Sudan.
Abyei is expected to be on the agenda at a second day of talks on Wednesday at the African Union headquarters in Addis Ababa. The U.N. Security Council has called on both sides to resume talks and end fighting or face sanctions.
The AU-brokered talks are the first since negotiations were broken off during the fighting last month.
However, diplomats expect no quick breakthrough as both sides are at loggerheads over a long list of disagreements from marking the disputed border and deciding on the status of Abyei to agreeing on oil export fees for South Sudan.
The landlocked new nation inherited much of Sudan's oil reserves and shut down production in January to stop Khartoum from taking oil for what the latter called unpaid export fees. (Reporting by Aaron Maasho, Hereward Holland and Ulf Laessing; Writing by Ulf Laessing and Alexander Dziadosz; Editing by Louise Ireland)
Our Standards: The Thomson Reuters Trust Principles.
