Jim Barry, chief investment officer of BlackRock Alternative Investors, which manages more than $175 billion (138 billion pounds), said investor sentiment had taken a hit and caution was warranted.

"I'd be very wary at this juncture about committing any capital, debt or equity, to the UK utilities space," said Barry, who is also the company's global head of real assets. "They're all well-capitalised as it stands, but it has added a risk."

Britain's main opposition Labour Party has laid out plans to take control of some key strategic assets including water, energy and transport if it managed to prise power from Theresa May's Conservative government.

Barry's team of more than 900 staff invest in real estate, infrastructure, hedge funds, private equity and private credit.

(Reporting by Simon Jessop; editing by Sinead Cruise)