Bank of Japan Gov. Haruhiko Kuroda said Thursday low profitability at financial institutions could sow the seeds of a new financial crisis, offering his strongest warning to date of the demerits of aggressive monetary easing pursued by major central banks.

Mergers and consolidation may be among options for financial institutions to boost profitability, Kuroda said in an unusually frank call for bolder steps to deal with the over-crowded regional banking sector.

Faced with low inflation and tepid economic growth, many central banks, such as the BOJ, the Federal Reserve and the European Central Bank, have adopted unconventional monetary easing steps since the global financial crisis in 2008.