Sudan has accused Israel of carrying out an air strike that killed two people in a car near the city of Port Sudan on Tuesday.
Foreign Minister Ali Ahmad Karti said one man was Sudanese, but the identity of the other passenger was unknown.
There has been no comment from Israel. But correspondents say Israel believes weapons are being smuggled through the region to Gaza.
Mr Karti said the air strike was an attempt to damage Sudan's reputation.
It was intended to disrupt the process of removing Sudan from the list of states that sponsor terrorism, he added.
Washington this year initiated the process to remove Sudan from that list after a peaceful January referendum in which the country's south voted to secede.
The car was hit about 15km (nine miles) south of Port Sudan on Tuesday.
There is confusion as to whether the car was hit by a plane, helicopters or a missile fired from outside Sudan.
Mr Karti said one of the victims was an innocent civilian and efforts were being made to discover the identity of the second man.
"The attack was carried out by Israel. We are absolutely sure of this," Mr Karti was quoted as saying by AFP news agency.
So far no-one has claimed to have carried out the attack.
"We heard three loud explosions," a source at Port Sudan airport told Reuters news agency. "Eyewitnesses told us they saw two helicopters which looked like Apaches flying past."
The car had been travelling into the city from the airport, one Sudanese official said.
In 2009, the Sudanese authorities said a convoy of people smugglers was hit by unidentified aircraft in Sudan's eastern Red Sea state.
There was speculation at the time that the strike may have been carried out by Israel to stop weapons bound for Gaza.
The then Israeli Prime Minister, Ehud Olmert, appeared to give credence to the idea that Israel was involved in that attack, saying: "We operate everywhere where we can hit terror infrastructure - in close places and in places further away."
Israel has not commented on the latest incident.
The BBC's James Copnall in Sudan says Hamas, the militant Palestinian group that controls the Gaza Strip, is on good terms with Khartoum.
There has been an uneasy peace in eastern Sudan for several years, following one of Sudan's many civil wars.
But the region is very underdeveloped, even by Sudanese standards, and there are fears about increased illegal activity there, our correspondent says.