(Adds details on flows, Japan and China holdings) Feb 16 (Reuters) - Foreign investors resumed selling U.S. Treasury bonds and notes in December, Treasury Department data on Tuesday showed, after they made net purchases in November. On a transaction basis, foreigners sold $20.7 billion in Treasuries in December, after buying $9.6 billion of them in November, the U.S. Treasury Department said. Total foreign holdings of U.S. Treasuries declined for a fifth straight month, with foreign investors holding $7.036 trillion in U.S. government debt at the end of December, down from $7.054 trillion at the end of November. During December the yield on the benchmark U.S. 10-year note rose from 0.847% to 0.912% as investors positioned for a faster-growing U.S. economy coming out of the COVID-19 pandemic. Total net inflows in long-term securities were $121 billion in December, down from $149.2 billion in November. For the 12 months ended Dec. 31, total net inflows in long-term securities were $505.7 billion, up from $389 billion for all of 2019, the Treasury Department said. Japan reduced its Treasury holdings to $1.257 trillion at Dec. 31 from $1.261 trillion the prior month, still the largest amount held by any foreign investor in U.S. Treasuries. Treasury securities held by China, the second-largest holder, declined to $1.062 trillion as of December from $1.063 trillion in November. (Reporting by Ross Kerber, Editing by Franklin Paul and Cynthia Osterman)