SEOUL, Jan 12 (Reuters) - South Korea's bond market saw the biggest monthly foreign capital outflow in almost four years in December 2022, central bank data showed on Thursday, because of an increase in the amount of bonds that matured at the end of the year.

In the local bond market, foreigners logged a net outflow of $2.73 billion in December, compared with a net $0.63 billion inflow in November, according to the Bank of Korea (BOK). It was the biggest outflow since January 2019.

"The amount of local bonds that reach maturity increases every March, June, September and December. In the last month, it was $5.2 billion," a BOK official said.

"The outflow was likely a temporary effect before investors set new investment plans at the beginning of a new year."

In 2022, foreigners bought a net $11.72 billion worth of local bonds, much smaller than $56.15 billion in 2021 and the smallest since 2019. (Reporting by Jihoon Lee; Editing by Himani Sarkar)