Remaining an EU member is vital for the U.K.'s long-term energy security and economic security as a Brexit could cost consumers an additional half a billion pounds a year, said Energy and Climate Change Secretary Amber Rudd on Thursday.
"The U.K.’s membership of the EU has helped keep our energy bills down," Rudd argued.
Leaving Europe’s internal energy market would result in a massive shock because the U.K. energy costs would likely increase by £500 million or more each year, she added.
Rudd advised that the best way to tackle Putin's use of natural gas as a foreign policy tool, in threats to cut supplies or drastically increasing prices, is through putting up a united front.
"We can’t let our energy security be hijacked as a political pawn to bring Europe to its knees. By working together in the EU each member state can stop this becoming a reality," she said.
Rudd highlighted the investment and job opportunities accompanying the EU.
"Being in the EU helps us attract billions and billions of pounds of investment in our energy system and supply chain," she said and added, "Taken together, this investment helps support 660,000 jobs in the U.K.’s energy sector."
"Does anybody really think all of that investment would continue if we left the EU, and with no extra costs?" Rudd asked.
Remaining in the EU is also about the U.K.'s status and power in the world, she argued.
"I firmly believe that within our position in the EU, we can influence the great geopolitical challenges of the day, to make the world a safe place for Britain," Rudd added.
On June 23, the U.K. will vote on the future of its EU membership.