Many European countries rely heavily on Russia for their natural gas. But the ministers fear the crisis in Ukraine, and their opposition to pro-Russian activists, could prompt leaders in Moscow to turn off the taps.

Japanese Trade Minister Toshimitsu Motegi said the G7 nations must work together to secure stable supplies of natural gas and other resources.

He said Japan is planning to resume operations at its nuclear plants, once their safety is confirmed, in an attempt to diversify energy resources.

Motegi told reporters the G7 ministers are hoping to send a clear and unified message that they will decrease their reliance on Russia.