Britain's energy minister says the Group of 7 Western powers is vowing to stop Russian President Vladimir Putin from using "energy as a weapon" in the increasingly violent Ukrainian crisis.

Ed Davey said energy ministers who met in Rome on Tuesday agreed to work out medium- and long-term policies that would reduce the level of dependence on Russia's oil and gas by much of Europe. Some details will be included in an upcoming statement.

Davey acknowledged such a strategy would take months if not years to implement. But he said "we have taken decisions to face up" to Putin and "disarm the Russian energy weapon" by reducing Europe's dependence on Russian energy.

The ministers were doing preparatory work for an upcoming G-7 summit.