Israel used unmanned drones to attack clandestine Iranian convoys in Sudan that were attempting to smuggle rockets into Gaza, Britain's Sunday Times newspaper reported.

The paper said that western diplomats confirmed that Israel attacked the Iranian truck convoys in late January and the first week of February in the remote Sudan desert, just outside the Red Sea town of Port Sudan.

The convoys had been tracked by agents from Mossad, Israel's overseas intelligence agency, the report added.

The Sudanese government said this week it was investigating the possibility that Israel was behind the deadly air strikes, but so far had found no proof.

Foreign ministry spokesman Ali Sadiq said there were two separate bombing raids against smugglers, killing about 40 people.