A diplomatic source told Reuters that Sudanese Army soldiers had fired on the convoy late Monday, apparently confusing the peacekeepers for rebels, but a spokesman for the U.N.-AU Mission in Darfur (UNAMID) said the incident was still under investigation.
No one from Sudan's armed forces was immediately available for comment, Reuters reported.
One civilian Sudanese driver was in critical condition after being shot seven times, UNAMID announced. The convoy was taking food and fuel to a UNAMID outpost near the town of Tine, close to the border of western Darfur and Chad.
A diesel truck and UNAMID armed personnel carrier also were damaged in the attack, according to the statement.
The attack comes at a time of heightened tensions in Darfur, in western Sudan, and neighboring regions of Chad. Sudan and Chad are accusing each other of harboring rebels dedicated to overthrowing their respective regimes.
Chadian air force planes bombed Chadian rebel bases close to west Darfur's capital El Geneina on Sunday, the second reported incursion into Sudanese territory in two weeks, according to a U.N. report.
The hybrid U.N.-AU force, which replaced a struggling AU mission on Jan. 1, has been working to restore stability in the region and allow aid groups to reach refugees. The plan is to bring 20,000 soldiers and 6,000 police to the region, but only one third are in place so far.
A low-key ceremony on Dec. 31 just outside the North Darfur capital of El Fasher marked the turnover, where African Union Gen. Martin Agwai replaced his green AU beret with one of U.N. blue.
U.N. Secretary-General Ban Ki-moon on Monday warned that the peacekeeping force was too small to deal with the deteriorating situation in Darfur, reported Reuters.
AU spokesman Noureddine Mezni said that the UNAMID force needs military helicopters and better ground transportation in order to patrol more areas and respond more quickly to conflicts.
"In an area like Darfur, the size of France, we cannot do the job properly without these things. We appeal to the international community and all those able to provide us with these things to do so as soon as possible," he said, according to the Associated Press.
An estimated 200,000 people have died since fighting began in early 2003 between rebels and what are though to be government-backed militias.