BEIJING, Oct 9 (Reuters) - China dramatically expanded its rare earths export controls on Thursday, adding five new elements and extra scrutiny for semiconductor users as Beijing tightens control over the sector ahead of talks between Presidents Donald Trump and Xi Jinping. The world’s largest rare earths producer also added dozens of pieces of refining technology to its control list and announced rules that will require compliance from foreign rare earth producers who use Chinese materials. The Ministry of Commerce’s announcements follow U.S. lawmakers’ call on Tuesday for broader bans on the export of chipmaking equipment to China. They expand controls Beijing announced in April that caused shortages around the world, before a series of deals with Europe and the U.S. eased the supply crunch. “The White House and relevant agencies are closely assessing any impact from the new rules, which were announced without any notice and imposed in an apparent effort to exert control over the entire world’s technology supply chains,” a White House official told Reuters on Thursday. The new curbs come ahead of a scheduled face-to-face meeting between Trump and Xi in South Korea at the end of October.