South Korea's foreign currency deposits reached an all-time high in July, marking the steepest monthly increase in seven months, driven by a substantial rise in dollar-denominated savings, according to data released by the central bank on Friday.

As of the end of July, residents' foreign currency-denominated deposits totaled $128.34 billion, up $15.01 billion from the previous month, the Bank of Korea reported. This figure represents the highest level since the central bank began compiling such statistics in June 2012 and also marks the largest single-month gain since a $15.88 billion increase last December. Resident foreign currency deposits have now risen every month since April.

The central bank's definition of residents includes South Korean citizens, foreigners who have lived in the country for more than six months, and foreign companies. The data excludes interbank deposits.

By currency, dollar-denominated deposits climbed by $11.12 billion to reach $108.92 billion, also the highest level since June 2012. Euro-denominated deposits increased by $2.22 billion to $8.06 billion, while yen-denominated deposits rose by $1.5 billion to $8.61 billion.

Corporate foreign currency deposits grew by $13.57 billion to $112.56 billion, whereas individual holdings expanded by $1.44 billion to $15.77 billion.

The Bank of Korea attributed the surge in foreign currency deposits primarily to increased income from exporting companies and funds held by local brokerage firms for investments in foreign bonds.