The Bank of Japan on Wednesday announced additional monetary easing saying it was boosting an asset-purchasing fund by 10 trillion yen ($128 billion) to 80 trillion yen.

The BoJ also kept interest rates at between zero and 0.1 percent in a unanimous decision, a statement said.

Following the announcement of the fresh measure, the dollar edged up against the yen, trading at 78.95 yen, from about 78.78 yen before the decision in Tokyo trade.

Tokyo shares also jumped, with the benchmark Nikkei 225 index climbing 1.32 percent, or 120.39 points, to 9,244.16.

The fresh easing measure came as Japan's export-dependent economy struggles to right itself following a succession of problems, including the March 2011 earthquake and tsunami disaster, the European debt crisis, slowing global demand and the strong yen.

Pressure on the central bank to take additional easing steps increased after the European and US central banks took action.

A the start of the month the European Central Bank announced a massive sovereign bond buy up, brushing aside German opposition to unleash a so-called "big bazooka" against the debt crisis.

A week later the Federal Reserve unveiled a new bond-buying programme that it said it would not back away from until it is happy the economy is on the right track and unemployment is falling. (AFP)