The Bank of Japan recently said it will be focusing more on holding foreign assets in safe and highly-liquid assets amid recent volatility in global markets for ensuring that it has enough of firepower to assist domestic banks in case they face trouble raising cash overseas.

The Bank of Japan will limit its holdings of foreign bonds to ones denominated in dollars, euros and British pounds, and primarily to those issued by the U.S. and major European nations, in a revision made to rules on managing its 4.35 trillion yen ($54 billion) in foreign assets. The BOJ will continue to invest the remaining funds in deposit with other central banks.

"International financial and capital markets have shown increased volatility in the wake of the global financial crisis," the central bank said.

"The BOJ decided it was appropriate to place increased emphasis on safety and liquidity when managing its foreign currency assets," it said.

The new rules will not lead to a big change in the currency composition of its foreign-asset holdings, Hideaki Ono, director-general of the BOJ's international division, told reporters and added the central bank has no plans for now to increase its foreign-asset holdings.