Japan's Finance Minister Katayama says decided on energy subsidy as an emergency step, adds FX movements have been driven partly by speculators

Says:

• Speculators can move easily due to the Bank of Japan and the summit.
• There has been some speculative trading in oil markets and authorities will do their utmost to respond to currency moves at any time. 
• The ministry is prepared to take necessary actions against market volatility and is watching financial markets with an extremely high level of vigilance.