SHANGHAI, Oct 15 (Reuters) - China’s central bank injected funds through medium-term loans into the financial system on Friday, while keeping the interest rate unchanged for the 18th month in a row. The People’s Bank of China (PBOC) said it was keeping the rate on 500 billion yuan ($77.66 billion) worth of one-year medium-term lending facility (MLF) loans to some financial institutions steady at 2.95% from previous operations. The cash injection effectively rolled over the same amount of maturing MLF loans due the same day, according to the statement. The central bank also injected another 10 billion yuan worth of seven-day reverse repos into the banking system on the day, offseting same amount of the short-term liquidity tool set for Friday. ($1 = 6.4380 Chinese yuan) Reporting by Winni Zhou and Andrew Galbraith Editing by Shri Navaratnam Our Standards: The Thomson Reuters Trust Principles.