Warlord Joseph Kony and some of his Lord's Resistance Army commanders are hiding in Sudanese-controlled areas of a disputed enclave in South Sudan bordering the Central African Republic and Sudan, the United Nations said.
In a report to the UN Security Council, Secretary General Ban Ki-moon said Sudan's government had indicated there were no elements of the group in the disputed Kafia Kingi enclave.
"However, credible sources suggest LRA leader Joseph Kony and senior LRA commanders have recently returned to seek safe haven in Sudanese- controlled areas of the enclave," Ban said on Tuesday.
Kony, who has been indicted for war crimes by the International Criminal Court in The Hague, waged a brutal guerilla war against the Ugandan government in the north of the country for nearly two decades, before fleeing into the jungles of central Africa around 2005.
A 5,000-strong African Union Regional Task Force - supported by 100 US Special Forces - has been hunting for Kony and LRA commanders accused of abducting thousands of children for use as fighters in a rebel army that earned a reputation for chopping off limbs as a form of discipline.
"The LRA is believed to have split into several highly mobile groups operating with a significant degree of autonomy in the Central African Republic and the Democratic Republic of Congo," Ban reported. "They are involved primarily in survival mode activities which entail attacking civilians, killing, looting and kidnapping. There have been no reports of recent premeditated mass killings or other grave human rights abuses," he said.
According to the UN Office for the Co-ordination of Humanitarian Affairs, 65 LRA attacks were reported in the first quarter of the year in the Central African Republic and Congo, during which 93 people were abducted and two killed.