Sudan denied Wednesday that its army opened fire on a convoy of U.N. peacekeepers attacked in Darfur barely a week into their new mission.

The U.N. said members of the Sudanese armed forces attacked a "clearly marked (U.N.) supplies convoy" near Darfur's border with Chad late Monday, critically injuring a Sudanese driver, destroying a fuel tanker and damaging an armored personnel carrier.

The U.N. said it had agreed with the government to launch an urgent investigation into the attack.

But several Sudanese newspapers quoted the military denying that its forces had opened fire on members of the U.N. mission to Darfur, which began Jan. 1 and is known as UNAMID.

"The army has not fired a single bullet at the UNAMID, by mistake or not," Sudanese military spokesman Khalid Sawarmy told the independent Al-Sahafa newspaper. "What is reported about this is totally untrue."

Some U.N. officials said the Sudanese army had attacked the peacekeepers by mistake, confusing them with Darfur rebels. Sawarmy said this sounded as if the army was finding an excuse to apologize for its error, and denied this was the case.

"Of course, we cannot apologize for a mistake that we didn't commit," he said.

The military gave no alternative explanation for the attack on the U.N. convoy.

UNAMID spokesman Noureddine Mezni said the rest of the convoy had safely reached the border outpost of Tine on Wednesday. He said such ground supplies convoys were needed because of restrictions on UNAMID flights. The U.N. says it has suspended most helicopter flights near the border because of fears aircraft could be caught in fighting between the Sudanese military and Darfur rebels or nearby Chadian forces.

The U.N. mission is the latest international attempt to quell fighting in the western Sudanese region, where more than 200,000 people have died and 2.5 million were chased from their homes since ethnic African rebels took arms against the Arab-dominated Sudanese government in 2003, accusing it of discrimination.

Sudan has been accused of obstructing the deployment of the new U.N. force. It has not accepted a Status of Forces Agreement, the legal framework under which peacekeepers can operate.

Mezni said negotiations on the agreement would resume in coming days.

The new joint force, which incorporates a previous African Union mission that suffered dozens of casualties, stands at about 9,000 troops and police, and is supposed to grow to 26,000. But the deployment is far behind schedule and Western countries have so far failed to commit heavy fighting equipment such as helicopters.