The yen is continuing near record highs
Global finance ministers have expressed concern at the "extreme volatility" of the yen, as the Japanese currency remained near 13-year highs on Monday.
The comments came from heads of the Group of Seven (G7) leading industrialised nations, but they stopped short of prescribing action.
The yen's rise continued to hit Japanese stocks, with the Nikkei index closing at a 26-year low on Monday.
Japan's government said it would now move to shore up the share market.
The yen hit a rate of 91.93 yen against the dollar on Monday. On Friday it had touched 90.90 yen against the dollar, its highest level since 1995.
The G7 leaders commented on the high value of the yen in a joint statement issued after talks in Tokyo.
They said they would co-operate as appropriate to bring stability to battered global markets, but did not give any specific details of how they hoped to lower the yen's value.
The yen's rise has concerned Japanese investors, who are worried about its impact on the country's main exporters, as it makes their products more expensive overseas.
As a result, Japan's main stock index, the Nikkei, fell on Monday to close at its lowest level since 1982.
Prime Minister Taro Aso said Tokyo would move to introduce tighter controls on the short selling of stocks, and also pledged increased bail-outs for the country's banks.
Short selling occurs when an investor borrows company stock owned by another investor, then sells the shares in the market, hoping the price will fall.
If the price does fall, they then buy the shares back at the lower price, pocketing the difference.
Other nations, such as the UK, have already moved to put a temporary ban on short selling in financial stocks.
Japan's Finance Minister Shoichi Nakagawa added that he would "continue to watch currency markets with great interest".
The rise in the value of the yen is being driven by two main factors.
Firstly, like the US dollar, it is seen as a haven buy in uncertain times.
Secondly, the yen has risen as a result of the end of the yen carry trade, in which traders used the yen to buy currencies with higher interest rates.
The yen carry trade has been unwinding due to the difference between Japanese rates and those elsewhere in the world narrowing.
This means that traders have pulled out of investments in countries such as Hungary and Iceland, buying back the yen in the process.