Former British foreign secretary David Miliband has said he could not envisage Britain pulling out of the European Union.
Speaking on RTÉ's Morning Ireland, Mr Miliband said the argument that being a member of the EU was "an intolerable burden" on the British economy does not make sense.
British Prime Minister David Cameron has called a referendum on Britain's membership of the EU for 2017.
Mr Miliband, who resigned as an MP in March to take up a role with the International Rescue Committee, said there seems to be "an arms race" within the Conservative Party between potential election candidates on the EU issue.
He said that while the British public might not like the EU, leaving the union was not the most salient policy issue for them.
Mr Miliband insisted that leaving the union would be a "massive turn back" for Britain, and rather than giving the country independence, it would instead leave it at the mercy of the financial markets.
He said that being outside the EU would diminish Britain's influence on both European and global affairs.
"There is three million jobs dependent on being part of the single market," he said.
"It's by European countries coming together on issues that you can make a difference."