European Union member states have agreed to ration gas this winter in an attempt to avoid an energy crisis generated by further Russian cuts to supply.

Energy ministers on Tuesday backed a voluntary 15% reduction in gas usage from August through to the end of March, the Guardian reported, but agreed to some opt-outs for island nations and countries little connected to the European gas network.

The deal came less than 24 hours after Russia’s state-controlled energy firm, Gazprom, announced a steep reduction in gas supplies through the critical Nord Stream 1 pipeline from Wednesday. The head of the European Commission, Ursula von der Leyen, said there was “no justifiable technical reason” for the cut.

A collective 15% gas savings target without exemptions would reduce gas consumption by 45 billion cubic metres. A senior EU diplomat said the plan would not hit that volume estimate in the event of a major supply crisis, but still added up to “significant reductions.”

In the event of a total shutdown of Russian gas or high demand, EU states can declare an energy emergency that triggers immediate mandatory savings.