CAIRO - A road crash, which left eight US citizens dead in the Upper Egyptian city of Aswan on Sunday, could have such a negative impact on the flow of US tourists to Egypt as terrorism, a Tourism Ministry official said on Monday. "The negative impact of road accidents could be destructive as that of terror attacks," warned Hesham Za'zou, an assistant Minister of Tourism. Za'zou was speaking at a meeting of the general assembly of the Union for Tourism Chambers late on Sunday as 21 US tourists injured earlier in the day were transported for treatment at the Cairo Nasser Institute. President Barack Obama was briefed on the accident. "All tour companies are asked to respect regulations of travel, otherwise they and the Egyptian tourism will lose," Za'zou said. He added that the tour companies would pay the costs of treatment of the injured and pay compensation to the families of the dead. A bus with 37 US tourists was on its way from Aswan to Abu Simbel, an ancient temple popular with tourists, crashed head-on with a truck laden with sand. The bus driver and the tour guide are said to be among those injured when the bus hit the stationary truck. "The cases of injured tourists are improving. Five of them were in critical conditions but they are doing well now," said the Health Ministry in a statement yesterday. The crash happened as the convoy was making the 115-mile trip to the temple at Abu Simbel from Aswan. Because road laws are not rigorously enforced in much of Egypt, and the roads are often poor, traffic mishaps are common.