TOKYO: The yield on Japan's 10-year government bond dropped to zero for the first time ever on Tuesday, the lowest among G7 countries, on the back of wild volatility on equity markets.

The note slipped four basis points Tuesday to zero per cent, continuing a downtrend sparked by the Bank of Japan's surprise move last month to slap a negative interest rate on some commercial lenders' deposits.

Before the unexpected decision, Japan's 10-year bond was paying a yield of about 0.2pc, similar to the current payout on a comparable German government bond.

By comparison, the United States pays about 1.7pc on a 10-year bond while hard-hit Greece must pay a nearly 10pc yield on its decade-long notes to attract wary investors.

The decline in the yield ─ effectively the rate of return for a bond if held to maturity ─ reflects rising demand for Japanese government bonds, and investors' worries about putting money into equities.

Bonds, and especially government bonds, are generally seen as super safe investments where capital is all-but guaranteed, even if they pay very little ─ or no ─ interest.

Stocks and commodities have got off to a terrible start in 2016, reflecting the increasingly gloomy outlook from policymakers ─ particularly for number two economy and key driver of world growth, China.

Tokyo shares tumbled more than four percent Tuesday, joining a global sell-off as a stronger yen dented exporters and after oil prices tanked again on fears of a worldwide economic slowdown.

On forex markets, the dollar briefly slipped below 115 yen, hovering around its lowest levels since 2014. Investors tend to buy the Japanese unit as a safe bet in times of uncertainty or turmoil.