WASHINGTON (Reuters) - The U.S. State Department said on Tuesday it was urging Saudi Arabia to be  fair and transparent  in its handling of any prosecutions stemming from a sweeping corruption probe that has resulted in the arrests of dozens of top Saudi officials. State Department spokeswoman Heather Nauert said the United States had no advance knowledge of the corruption crackdown that unfolded over the weekend and resulted in the detention of members of the royal family, ministers and investors, including prominent billionaire businessman Alwaleed bin Talal.  We continue to encourage Saudi authorities to pursue the prosecution of people they believe to have been corrupt officials; we expect them to do it in a fair and transparent manner,  Nauert told a briefing.  We call on the government of Saudi Arabia to do that.  Nauert said the United States had received assurances from the Saudi government that it would do so, but another U.S. official later told reporters that she had misspoken and that they had no such assurances that they could discuss in public. Asked about Saudi Arabia s increasingly tough talk toward Iran and Lebanon, Nauert pointed to what she said was Iran s destabilizing activity and the Lebanese Hezbollah group s past record of attacks against U.S. military personnel. Saudi Arabia accused Lebanon on Monday of declaring war against it because of aggression by Hezbollah, the Lebanese Shi ite group backed by Iran. Saad al-Hariri, the Saudi-allied Lebanese prime minister, resigned on Saturday, blaming Iran and Hezbollah in his resignation speech. Nauert told reporters that Lebanon was a strong U.S. partner. Hezbollah has influential ties across Lebanon. Hariri s coalition government, which took office last year, grouped nearly all Lebanon s main parties, including Hezbollah. Michel Aoun, a Hezbollah ally, is president.  The United States strongly supports the legitimate institutions in the Lebanese state,  Nauert said.  We expect all members of the international community to respect fully those institutions and the sovereignty and political independence of Lebanon.  