Sudanese armed forces say rival southern forces were behind Friday's attack on U.N. peacekeepers and Sudanese soldiers in the oil rich Abyei region.
But a spokesman for the Sudan People's Liberation Army (SPLA) tells Reuters news agency that his forces were not involved in the attack.
U.N. officials say two people were wounded in the incident.
Troops from the north and south had agreed to conduct all patrols jointly in the Abyei area.
The north and south are attempting to settle several key issues before the south becomes independent on July 9, including the fate of Abyei.
A referendum on whether Abyei would join the north or the south was scheduled in January, but did not take place because the two sides could not agree on who was eligible to vote.
Some information for this report was provided by AP, AFP and Reuters.