Japan Post, the world’s biggest financial institution, has started to enforce a law on the statute books since 1947 that enables it to forcibly convert customers’ postal savings into government bonds.

In the past, the post office has turned a blind eye to deposits above the Y10m statutory limit, a finance ministry official said. But it has begun to apply the law strictly in the run-up to privatisation in 2007 to quell criticism that it is abusing its monopoly position to trample private competition, he said.