The Bank of Japan on Tuesday added to monetary stimulus for the second time in two months, the fastest pace of easing in nearly a decade, as it moved to shore up an economy at risk of contraction.

The central bank expanded its asset-purchase fund, its main policy tool, by ¥11 trillion, bringing the total to ¥91 trillion in a widely expected move, while keeping its key short-term interest rate steady at around zero to 0.1 percent.

BOJ Gov. Masaaki Shirakawa may face pressure to keep easing after data released Tuesday showed the steepest fall in industrial output since last year's Great East Japan Earthquake, adding to the likelihood of an economic contraction.