BEIJING -- The People's Bank of China (PBOC), the central bank, said Monday that it injected 100 billion yuan ($15.4 billion) into the market in December through medium-term lending facility (MLF).

A total of 13 financial institutions received money from the central bank for six months at an interest rate of 3.25 percent.

"The move was aimed at keeping liquidity reasonably abundant," said the PBOC.

Last month, small institutions got a total of 135 million yuan in over-night loans from the PBOC's local branches via standing lending facility (SLF) at 2.75 percent.

MLF and SLF are liquidity tools designed for cash-strapped commercial and policy banks to borrow from the central bank using securities as collateral, at rates set by the PBOC.