KHARTOUM (AFP) - Sudan is investigating the possibility that Israel was behind deadly airstrikes this year against suspected Gaza-bound arms convoys, but so far it has found no proof, a government official said. Foreign ministry spokesman Ali Sadiq said there were two separate bombing raids against smugglers in a remote desert area near the Red Sea town of Port Sudan in January and February, killing about 40 people. "First we suspected it was the United States, but we received assurances it was not them, and we are investigating other possibilities, including Israel," Sadiq told AFP. The New York Times, citing unnamed US officials, reported on Friday that Israeli warplanes were behind the attack. Two American officials who are privy to classified intelligence assessments added that Iran had been involved in the effort to smuggle weapons to Gaza, the newspaper reported. Hamas on Friday denied that the alleged weapons convoys were destined for the Palestinian movement. "First of all we are not sure any convoy has been hit, but it is ironic to link these convoys to Hamas," one of the movement's leaders, Salah al-Bardawil, told AFP. "Should it turn out that there were raids and a high number of people killed, this would mean Israel is seeking to use the opportunity to blame Hamas and hit Sudan," he said. The fact that the Gaza Strip is not a neighbour of Sudan, with Egypt in between, "shows these are false claims," he added. An Israeli military spokesman has refused to confirm or deny involvement, saying only: "We are not in the habit of reacting to this sort of report." Israel fought a devastating 22-day war with Hamas in December and January, and has vowed to stop the flow of weapons into the Palestinian enclave. "We operate in many places near and far, and carry out strikes in a manner that strengthens our deterrence," Israel's outgoing Prime Minister Ehud Olmert said after reports of the bombing raids emerged. The New York Times said intelligence analysts noted that the strike on Sudan was consistent with other measures Israel had taken to secure its borders. The pan-Arab newspaper Asharq Al-Awsat quoted Sudanese officials on Friday as saying the convoys were transporting Eritrean migrants. News of the alleged raids surfaced as Sudanese President Omar al-Beshir flouted an international arrest warrant against him by going on a series of foreign trips.