The Bank of Japan embarked on an aggressive monetary policy to end years of deflation in the world's third largest economy, saying it would pursue quantitative easing as long as needed to achieve its 2 percent inflation target.

The central bank concluded a two-day policy meeting, the first under new Governor Haruhiko Kuroda, with a statement that its bond-buying program would target Japanese government bonds off all maturities. The current program targets bonds with a maturity of three years. It said it would bring forward the timing of open-ended asset purchases.

Japan's benchmark stock index trimmed its losses after the decision, while the yen weakened against the dollar. Japanese shares have surged since mid-November and the Nikkei on Wednesday enjoyed its biggest one-day rise in two months on expectations for aggressive monetary easing.

Those expectations have also knocked the yen down about 16 percent against the dollar since mid-November, although the currency has risen in recent days on some caution as to whether Kuroda would be able to build a consensus among the nine members of the BOJ policy board for an unorthodox monetary policy.

Japan has suffered from persistent deflation and has slipped in and out of recession in recent years. Prime Minister Shinzo Abe, whose ruling Liberal Democratic Party returned to power following elections in December, has pledged to revive the Japanese economy and pushing for a much bolder monetary policy than the BOJ has pursued in the past is part of his plan.

Kuroda has pledged to do whatever it takes to achieve the 2 percent inflation target, adopted by the central bank in January, within two years. There is some skepticism among economists as to whether the target can be achieved. Jesper Koll, head of Japanese equity research at JPMorgan Securities, believes it can be. "You've got credit growth, you've got demand for credit and you will find that within 15 to 18 months, consumer price inflation in Japan will be well in excess of 1 percent," he said.

Latest data shows that Japan's core consumer prices fell 0.3 percent in February from a year earlier. The BOJ meets again on April 26.