The UK's GDP could be 2.2 percent smaller by 2030 if it leaves the EU - according to a new study by policy think tank Open Europe.

The group explored a number of possible scenarios that could happen as a result of a 'Brexit' - the most damaging is a situation where Britain leaves the union and fails to strike a trade deal with its former EU partners, and it is forced to introduce protectionist policies.

The report also argues that Britain's economy could potentially benefit from leaving - growing by 1.6 percent if it managed to strike liberal trade arrangements with the EU and the rest of the world. It warns that such agreements would involve difficult political negotiations.

According to the report all of the three best possible outcomes for the economy would be dependent on the state not curbing the inflow of migrants into the UK.

Open Europe says that a change in GDP of minus 0.8 percent - and plus 0.6 percent would be the most likely outcome of a British exit.

Trade with EU countries is crucial to the health of the UK's economy - the report comments that after a British exit, large industries would still need to live up to the "EU’s high regulatory standards" when dealing with EU countries. The UK would no longer have a say in these policies.

The study says that a loss of voting rights in Europe could have a negative impact on a number of sectors of the UK's economy - particularly financial services.

Lord Leach of Fairford, Open Europe Chairman commented on the report's findings:

"Brexit is unlikely to be the cataclysmic event some have claimed. However, transforming Britain into the deregulated, free trading economy it would need to become outside the EU sounds easy in theory, but in practice could come up against some serious political resistance within the UK itself."