The European Union is considering making a more explicit link between energy and fish as the Brexit negotiations enter a critical phase, RTÉ News understands.
A number of sources have confirmed that the EU's chief negotiator Michel Barnier will seek to use the leverage of the EU's energy market as a potential way of unblocking the UK's resistance to granting European fishing fleets ongoing access to British waters.
It is understood Mr Barnier has privately acknowledged a potential link between continued access to the EU's energy market which diplomats say is potentially highly valuable to the UK and the fisheries aspect of the negotiations, which remains deadlocked.
"The position of the UK [on fish] is quite strong," an EU official said, "but there are also connections. Sometimes the UK is interested in having access to [the single market] on energy."
One EU diplomat told RTÉ News: "The energy market is considerably more valuable to [the UK] than the entire fish stock that they're talking about. Barnier seems to have paused the discussions on energy for the moment, and this link has been made with fish."
As an EU member state, the UK has been part of the single energy market trading energy to and from the European continent via electricity and gas interconnectors.
There is an increasing view in Brussels that this is a valuable market for the UK which could be implicitly linked to fisheries.
The fisheries negotiations have been stalled with the EU seeking to retain as much access to UK waters and as much quota for species that straddle EU-UK waters as possible.
The UK has insisted that as an independent coastal state after Brexit it should control the lion's share of both access and quota share.
It's understood that negotiations on the access the UK will have to the EU's energy market as a third country were close to being finalised.
However, officials say the EU has been reluctant to close individual chapters of the talks as that would weaken the EU's position on the most difficult outstanding issues, such as fisheries, the so-called level playing field, and governance.
Officials caution that the EU will not use energy as a "hostage" in order to secure concessions on fisheries but that holding out on closing the energy chapter would strengthen the EU's hand.
"In that context, there's no point in finalising things like energy, which are in the UK's interest," according to one official familiar with the negotiations.
Energy generated by wind, electricity and gas is traded across the EU's internal energy market via interconnectors using electronic spot trades.
Once the Brexit transition period ends on January 1 the UK will not enjoy the same access to the market.
Negotiations have been underway that would grant the UK limited, but still valuable, access to the EU's energy market.
According to a European Parliament report in 2017, the EU-UK electricity and gas market was worth some €6bn in 2015, more than 80% of which was in natural gas.
The UK has become a significant importer of natural gas from the EU and Norway but is an exporter of gas to Ireland and Belgium.
The UK sells electricity to France, Ireland and the Netherlands but has also been a net importer of electricity from France and the Netherlands depending on demand and weather fluctuations.