South Korea's M2 money supply expanded at the fastest clip in almost five years in May, due mainly to increased liquidity of households, central bank data showed Wednesday.

The M2 surged 9.3 percent on-year to 2,170.5 trillion won ($1.9 trillion) in May, quickening from a 9 percent increase in the previous month, according to the Bank of Korea.

The on-year growth marks the fastest increase since July 2010 when the M2 expanded 9.3 percent.

From a month earlier, the country's M2 rose 1 percent on a seasonally adjusted basis, compared with a 1 percent growth in April.

M2 includes currency in circulation, as well as types of deposits with a maturity of less than two years at lenders and non-banking financial institutions. It does not cover those with a maturity of two years or longer, government bonds or corporate bonds.

By sector, households posted one of the biggest expansions, growing 9 trillion won from the previous month.

In a separate statement, the central bank forecast M2 to have increased in the low 9 percent range in June in tandem with growing credit in the private sector. (Yonhap)