The dollar index, which measures the currency against the yen, euro and four other peers, was flat at 104.70, below the 105.79 high from Wednesday, a level not seen since late 2002.

The yen has hit 24-year lows - beyond 135 to the dollar - this week and rising bond yields have pressured the Bank of Japan yield curve control

The BoJ is estimated to have spent $5.2 billion on Wednesday buying bonds to defend its 10-year yield ceiling as 10-year futures endured their worst plunge in close to a decade.

There's speculation the prospect of significant US interest rate rises and the yen’s slump may force the Bank of Japan's hand on policy tightening

Observers say speculators betting on a Bank of Japan capitulation amid tightening at other global central banks have been attacking the bonds

The Bank of Japan ramped up bond buying on Tuesday in a bid to keep the yield on 10-year government bonds at a 0.25% cap, amid renewed pressure from rising global interest rates

Bank of Japan Governor Haruhiko Kuroda said the yen's recent sharp declines are negative for Japan's economy, shifting a long-held stance.

The Japanese yen, which has lost over 14% against the dollar so far this year, slipped to a 20-year low versus the dollar on Thursday

While conceding his words may have been inappropriate, Bank of Japan governor Haruhiko Kuroda said the remark was intended to help explain the need for more wage growth

Unlike its US and European counterparts, the BoJ does not face a trade-off between the need to tame inflation and support the economy, Kuroda says

The central bank risks upsetting the public as the weak yen drives up the price of imported goods going into Japan's upper house election expected on July 10

The core consumer price index, which excludes volatile fresh food prices but includes fuel costs, jumped 0.8% in March from a year earlier, data showed