Walid Hamid, spokesman for the Sudan People's Liberation Movement (SPLM) which dominates a newly formed southern government, said the Lord's Resistance Army (LRA), whose leaders are believed to be hiding in the vast south, had responded through the Internet to an SPLM offer to mediate talks.
"The (southern) Vice President Riek Machar said that they have agreed for the government of southern Sudan to mediate," Hamid said, adding no further details were available about the contact.
He said no direct contact had been made.
The International Criminal Court in The Hague issued its first warrants for five top LRA leaders in October, which observers had said ruled out the possibility of restarting failed peace talks between the group and the Ugandan government.
The former southern Sudanese rebel SPLM fought a bitter civil war for two decades for greater autonomy from the north, which was achieved in a peace deal in January. Sudan accused Kampala of arming the SPLM during the conflict and Uganda said Khartoum was arming the LRA.
But in September the SPLM joined a new coalition government in Khartoum, prompting a new agreement allowing Ugandan troops free access to track LRA rebels in southern Sudan and to use helicopters in their search.
The LRA has since been on the move, attacking civilians more frequently in the south and targeting international aid workers. On Friday the group attacked near the Uganda-Sudan border killing 10 people on their way to the market.
Senior SPLM sources said a further request for a face-to-face meeting had been made, but they were awaiting a reply.
The LRA, led by self-proclaimed mystic Joseph Kony, has kidnapped more than 20,000 children who are forced to become fighters and work as porters or sex slaves.
The cult-like group has no clear political aims and has terrorised communities in northern Uganda for almost two decades, forcing more than 1.6 million to flee their homes.