"I'd like to step down on March 19 when the terms of the two deputy BoJ governors end," Masaaki Shirakawa told reporters in Tokyo, according to Dow Jones Newswires.

Japan's top central banker added that he hoped his successor would be sworn in at the same time as a new slate of deputy governors, several news reports said, making no direct reference to friction with Tokyo.

Shirakawa had been expected to leave when his term expires on April 8, after Japan's new Prime Minister Shinzo Abe openly said he wanted to replace the country's top central banker.

The 58-year-old premier has also threatened to change a law mandating the bank's independence if it does not fall into line with his government's demands for aggressive easing measures.

It was not immediately clear if the hawkish premier had accepted Shirakawa's early departure.

Last month, the under-pressure BoJ said it would adopt a two percent inflation goal demanded by the country's new government in a bid to beat the deflation that has haunted the world's third-largest economy for years.

It also unveiled an unlimited asset-purchase scheme -- similar to the US Federal Reserve's quantitative easing -- to start next year.

But days later, Shirakawa cast doubt on the target, and said pressure on central banks has "risen globally more than ever".

The head of Germany's Bundesbank Jens Weidmann warned last month over what he described as government meddling in monetary policy.

"We are witnessing disturbing abuses... where the new government is interfering massively in the affairs of the central bank, calling forcefully for a more aggressive monetary policy," he said, citing Japan as an example.