Deighton, who was appointed commercial secretary to the Treasury in January, has been drafted in to work with the Department for Energy and Climate Change (DECC) as it negotiates with EDF.
The French firm last month received planning permission to build a new power plant at Hinkley Point in Somerset, but the scheme has become snarled in talks over a strike price for the electricity produced at the site.
EDF is also looking for a replacement partner in the £14bn project after Centrica pulled out in February.
A DECC spokesperson played down the significance of Deighton’s involvement, stressing that the department’s head civil servant Stephen Lovegrove, who took up his role in January, remains at the helm of the talks with EDF.
“DECC has always led the negotiations with EDF and continues to do so. Lord Deighton is the lead minister at HMT and has been working alongside DECC, this is nothing new,” the spokesperson said in a statement.
The government’s latest nuclear strategy document last month suggested that the UK’s nuclear pipeline had fallen behind its target to generate 16 gigawatts more power from nuclear sources by 2025.
DECC was the focus of a mini-reshuffle last month. Energy minister John Hayes was moved to a role in David Cameron’s Downing Street team after just seven months in the department, while business minister Michael Fallon picked up the energy brief.
Deighton, a former Goldman Sachs banker who was chief executive of the London Organising Committee of the Olympics Games (Locog), remains part of the Treasury team.