LEAVING the EU with Boris Johnson's Brexit deal would cost the UK £70 billion in 10 years, a new study has found. 

The National Institute of Economic and Social Research (NIESR) found that withdrawing from the bloc with the agreement would leave GDP 3.5% lower than if the UK continued its membership. 

The outlook from the independent forecaster is one of the first looks at the impact the Prime Minister's deal could have on the economy

NIESR warned the deal "would reduce the risk of a disorderly outcome, but eliminate the possibility of a closer trading relationship with the EU".

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The researcher added that new barriers would "hinder goods and services trade with the continent leaving all regions of the United Kingdom worse off than they would be if the UK stayed in the EU".

The report found the updated withdrawal agreement was a little worse for the economy than the initial deal drawn up by the EU and former PM Theresa May (below). The researcher predicted that first agreement would have left UK GDP 3% lower within 10 years.

The National:

According to the researcher, the economy is already feeling the impact of Brexit. "The economy is estimated to be 2.5% smaller now than it would otherwise have been as a result of the 2016 Brexit vote," the report stated.

A spokesman for the Treasury said: "We are aiming to negotiate a comprehensive free trade agreement with the European Union, which is more ambitious than the standard free trade deal that NIESR has based its findings on."