WASHINGTON, Jan 5 (Reuters) - U.S. Treasury Secretary Steven Mnuchin phoned New York Stock Exchange President Stacey Cunningham to tell her he disagrees with the NYSE's decision to reverse course on delistings of three Chinese telecoms firms, a source familiar with the matter said on Tuesday.

Plans for the delistings of China Mobile, China Unicom and China Telecom were prompted by a White House executive order banning U.S. investment in Chinese military-linked companies.

But in a shock reversal, NYSE said it no longer will pursue the delistings following new regulatory consultations. (Reporting by David Lawder Editing by Chris Reese)