The yen has rallied against the dollar after Japanese authorities intervened in the currency market. It's the first time in 24 years that Japan has waded into the currency market to buy yen -- which briefly climbed back to the 140 level.

The dramatic move came hours after the yen had tumbled to the upper 145-yen level against the greenback.

Traders had been dumping the Japanese currency following another US rate hike and a decision by the Bank of Japan to keep its easy money policy firmly in place.

A senior finance ministry official said the intervention is designed to halt the slide.

Concern about the widening gap between interest rates in Japan and the US has prompted a major sell-off of the yen in recent months.

The currency has shed around 20 percent of its value against the dollar this year -- drastically raising import prices and straining household budgets.