KUALA LUMPUR, Jan 19 (Reuters) - Malaysia's central bank on Thursday unexpectedly kept its benchmark interest rate unchanged at 2.75%.

"Today's decision allows the monetary policy committee to assess the impact of the cumulative past OPR adjustments, given the lag effects of monetary policy on the economy," Bank Negara Malaysia said in a statement.

All but one of 27 economists polled by Reuters expected the bank to raise the rate to 3%. (Reporting by A. Ananthalakshmi; editing by Christian Schmollinger)