European Union member states have made clear that any post-Brexit agreement to reintegrate the United Kingdom into the bloc’s internal energy market will be contingent on London making financial contributions to support poorer EU economies, according to diplomats and internal EU documents.

The stance underlines growing demands in Brussels that deeper cooperation after Brexit should come with commensurate fiscal commitments from the UK.

The EU’s position is emerging ahead of the launch of formal negotiations on British participation in the EU’s electricity market, which both sides have agreed could substantially reduce the hundreds of millions of pounds added to energy trading costs since Brexit.

Renewable energy groups and interconnector operators in the UK have long argued that closer alignment with the EU’s market-coupling mechanisms could lower wholesale electricity prices and improve supply security.

However, diplomats said EU capitals are debating how large a British contribution should be, with some member states advocating that the UK pay into EU cohesion and support funds as part of the terms for market access.

The requirement reflects a broader principle in Brussels that non-member partners should help underwrite the operation of shared infrastructure and the economic benefits anticipated from deeper integration.

Officials in London have declined to comment on the specific demands but argued that closer cooperation on electricity trading would deliver “real benefits to British businesses and consumers,” including attracting investment and lowering energy costs.

UK energy sector representatives agree, noting that current arrangements under the post-Brexit Trade and Cooperation Agreement impose significant inefficiencies.

The UK’s National Grid has told a parliamentary committee that the decoupling of energy market systems since Brexit has already added substantial costs to power trading, costs that ultimately flow into consumer bills.

The possibility that financial contributions will be tied to future cooperation adds a political dimension to energy talks and could require careful negotiation in London given sensitivities about sovereignty and fiscal commitments.

EU negotiators plan to finalise their mandate for talks in the coming months, meaning the question of UK contributions could shape the early stages of detailed discussions on energy cooperation.

As both sides prepare to explore ways to align electricity trading and emissions-trading schemes, the financing issue highlights the ongoing complexity of resetting the UK-EU relationship after Brexit.