Sudan has admitted that its forces were involved in an attack on peacekeepers in the troubled Darfur region.
The peacekeeping mission in Darfur is under-strength
The military apologised, saying the attack was the result of a "shared mistake" but adding the UN should have informed it of the convoy's movements.
Sudan's UN Ambassador Abdalmahmoud Mohamad earlier denied responsibility, saying the incident happened in an area where rebels were active.
The US and the UK have again accused Sudan of blocking the UN mission.
Sweden and Norway have dropped plans to send 400 troops to the region to do critical engineering work after Sudan refused to accept non-African troops.
UN peacekeeping chief Jean Marie Guehenno has told the UN Security Council that a local Sudanese army commander on the ground had contacted the UN and claimed responsibility for the attack on a supply convoy.
Mr Mohamad initially denied the reports, saying the rebels and their supporters had most to gain from such an attack.
But the Sudanese state news agency Suna later quoted a military spokesman admitting that a mistake was made.
"The Western Sudan Military Command has provided an apology to the representative of [joint UN-African Union force] Unamid in the region and the apology was accepted, in recognition of the dual mistake committed," the spokesman said.
He added that the convoy had failed to ask permission to go through the area of the attack, and should not have been travelling at night.
However, the UN says it did tell the Sudanese army about the convoy's route in advance.
A civilian Sudanese driver is in a critical condition after being shot seven times in the attack, Unamid said.
It said its peacekeepers had not fired back and there were no UN casualties.
The convoy had been carrying fuel and food to a joint United Nations-African Union outpost in the west of Darfur.
UN Secretary-General Ban Ki-Moon condemned the strike "in the strongest terms".
The attack is the first time the new peacekeeping operation has come under fire since the UN took over last week.
Unamid is due to become a 26,000-strong force but for the moment has just 9,000 troops.
Speaking on Wednesday, Mr Guehenno said the force would have to make the best of a difficult situation.
"Five months after the adoption of Resolution 1769 [establishing the force], we do not yet have guarantee or agreements from the government on basic practical issues," he said.
"The mission itself will not have the personnel or assets in place to implement its mandate for many months, even in the best-case scenario."
Tensions have been escalating in the area over the last few weeks.
There have been violent clashes between the Sudanese government and rebel groups.
Neighbouring Chad has been accused by Khartoum of bombing villages in the area, and each country accuses the other of sheltering rebel movements dedicated to overthrowing their respective regimes.
At least 200,000 people have been killed and two million forced from their homes in the five-year conflict.