The Bank of Japan on Thursday eased its monetary policy, boosting the size of its asset purchase program by another ¥5 trillion, raising its total funds to ¥55 trillion, citing the current instability in global financial markets and economies, as well as the yen's relentless rise.

The monetary easing was agreed by an 8 to 1 majority vote at the BOJ Policy Board, which also unanimously agreed to maintain the key interest rate at around zero to 0.1 percent.

"Care is necessary because of the risk that the economic and price outlook will deteriorate further depending on developments in global financial markets and overseas economies," the BOJ said in a statement following the Policy Board's one-day meeting.