The decision came days after the frontrunner to become Japan's next prime minister vowed aggressive monetary easing to fix the nation's economic woes. The bank also kept interest rates unchanged at between zero and 0.1 percent.

However, the BoJ said Japan's economy "has been weakening somewhat" amid slowing in exports and factory output.

The country's economy contracted in the July-September quarter, nudging Japan towards recession.

"Japan's economy is expected to remain relatively weak for the time being," the BoJ said in a statement, adding that the European debt crisis, an unsteady US economic recovery and an export-denting territorial spat with China have all weighed on the country's prospects.

"There remains a high degree of uncertainty concerning Japan's economy," the statement added.

In October, the BoJ said it would expand an asset-purchase programme -- its main policy tool -- by 11 trillion yen ($138 billion) to 91 trillion yen, the second expansion of the programme in as many months.

Pressure for further action spiked last week as Shinzo Abe, leader of the main opposition Liberal Democratic Party, called on the bank to usher in "unlimited" easing and vowed to strike an agreement with the BoJ on new policy measures if he takes the country's top political job next month

Japan will hold general elections on December 16 that are widely expected to see Prime Minister Yoshihiko Noda and his centre-left Democratic Party of Japan lose power.