The Palestinian Authority ordered an urgent investigation into several border officials at the Gaza-Egypt crossing on Saturday. European monitors said the inquiry was due to concerns they had about the return to Gaza of at least 10 terrorists. Mohammed Dahlan, the Palestinian official overseeing the crossing, paid a surprise visit to the border on Saturday, officials said, just a week after he took control of the Palestinians' first international border. Dahlan ordered an inquiry into border officials he accused of violating orders and the US-brokered agreement, officials said on condition of anonymity because they were not authorized to discuss the issue. He also made the border authority the top security force at the crossing, an attempt to eliminate problems caused by competing security forces, the officials said.