Japan intervenes in currency markets and yen weakens 5%
The Japanese government has intervened in the currency market to weaken the yen after it hit a post-war high.
The move resulted in the yen weakening as much as 5%. It was recently trading at 79.33 against the US dollar compared with 75.31 in early Asian trade.
A strong yen hurts Japan's export-led economy as it makes goods more expensive to foreign buyers.
Finance minister Jun Azumi said the yen's strength did not reflect the true state of Japan's economy.
He said that speculation in the foreign exchange (Forex) market, and concerns about the strength of the US and European currencies, had pushed the yen to unrealistic levels.
"I have said many times, if Forex moves do not reflect the economic fundamentals and speculative moves last, Japan will take firm measures," Mr Azumi explained on Monday.
The yen's rise has been driven in part by the fact that it is currently being considered a "safe-haven" asset.
The on-going debt crisis in Europe, coupled with fears of a slowdown in the US has seen an increasing number of investors shift from dollars and euros and starting buying up the yen and yen-denominated assets.
Faced with a strengthening yen, Japanese authorities have already stepped into the currency markets earlier this year.
In March, Japan joined forces with other Group of Seven, or G7, nations as it attempted to stem the yen's rise. That was followed by a move in August when Japanese authorities sold the yen in the markets.
However, those moves had only a limited impact as the yen continued its rise, despite weakening for a number of trading sessions.
Analysts said the latest intervention would probably have similar results.
"This will provide only a temporary support, as a lot of the factors that are keeping up the pressure on the yen are external," Philip Wee of the DBS Bank told the BBC.
"Intervention is about smoothing volatility rather than reversing trends."