Yen surges, analysts suspect official Japanese intervention

The Japanese currency also tumbled sharply against other peers, falling over 2% against each of the euro and pound.

In real terms the yen is trading near record lows and has been under pressure for years thanks to Japan's low interest rates and worries that Prime Minister Sanae Takaichi wants to suppress borrowing costs to fund spending increases.

Her government has said that the weak yen has started harming the economy, via higher import costs.

Japanese authorities spent more than $70 billion in dollar-selling intervention in April and May though the yen soon gave back those gains.

"Given the circumstances, it is reasonable to think that intervention was likely conducted," said Yuji Saito, executive advisor, SBI FX Trade, in Tokyo.

"The key question is whether authorities will keep pushing until the dollar breaks below the 155-yen line. We want to gauge that as just how serious the government is about defending the currency."