WASHINGTON (Reuters) - U.S. Secretary of State Rex Tillerson has spoken to Saudi Foreign Minister Adel al-Jubeir about the situation in Saudi Arabia, a U.S. State Department spokeswoman said on Thursday, where a crackdown on corruption has led to dozens of arrests.  State Department spokeswoman Heather Nauert also said the U.S. charge d affaires in Riyadh met on Wednesday with Saad al-Hariri, who resigned as Lebanese prime minister while in Saudi Arabia. Asked about reports Hariri was being held in the kingdom, Nauert declined to say where the meeting took place or to elaborate on Hariri s status. She described the talks as  sensitive, private, diplomatic conversations.  In his conversation on Tuesday with Jubeir, Nauert said, Tillerson urged that the Saudi government conduct any corruption prosecutions  in a fair and transparent manner.  Saudi authorities have arrested dozens of royal family members, officials and businessmen in the anti-corruption crackdown that began on Saturday. They face charges ranging from money-laundering to extortion. The line between public funds and royal money is not always clear in Saudi Arabia, an absolute monarchy ruled by an Islamic system in which most law is not systematically codified and no elected parliament exists. The Trump administration has endorsed the purge, cementing a dramatic strengthening in the relationship under U.S. President Donald Trump that in part has been driven by both governments  determination to confront Iran s growing regional power. Many experts see the crackdown as a move by Crown Prince Mohammad bin Salman, who heads a new anti-corruption body, to amass more power to enact political, economic and social reforms and to ensure that he succeeds his father, King Salman. 