The European Commission has published a report, the ‘Cincinnati Effect’ which claims that the world’s economic growth has slowed in recent years due to the “copenhagens” that have been introduced in the bloc.

The report has been criticised by economists, who say it is biased towards the big economies of the bloc, with its emphasis on the UK.

“It doesn’t take into account the fact that in the UK, the government is already planning to introduce a ‘soft Brexit’, in which the UK will remain a member of the single market and customs union,” Professor Michael O’Brien from the Centre for European Reform told BBC Radio 4’s Today programme.

The UK was an EU member until the UK voted to leave in June 2017.

Professor O’Brien said that if the UK was still a member, it should be able to negotiate its own terms for a trade deal, which could be better than the current “treaty of the future” arrangement.

“What is being proposed is a deal that is much better than what has been offered to the UK in the past and which is already well in place in some of the other EU member states,” he said.

“We need to see that, because the whole concept of what is being called the ‘Brexit’ is based on a false assumption.”

“What we are saying is that, by taking a ‘take it or leave it’ approach to Brexit, we will have missed out on some of what has made the UK great,” Professor OBrien added.

The Cincinnati Effect is part of a report entitled “The UK’s Economic Performance: From ‘Cologne Effect’ to ‘Cork Effect'”, which is part a joint report by the OECD and the International Monetary Fund.

“In the past, the UK has had a great relationship with the EU,” Professor George Kelling, the OECD’s director-general, told Today.

“Now, if you look at the UK’s performance, it is in decline.”

“We are not seeing the kind of growth we would expect from a relationship like that, and that is why it is very important for the EU to do more to support our economies,” he added.

In a statement to Today, the EU Commission said that it was “in the process of preparing the report”.

“We do not see the Cincinnati Effect as a negative factor,” the statement said.

It added that the Commission would provide an update to the report “as soon as possible”.