The Irish premier has been slammed for threatening to ban British planes from his nation’s airspace after Brexit if the UK takes back control of its territorial fishing waters.

The ultimatum comes as the International Monetary Fund (IMF) warns that Ireland will bear the brunt of a £200 billion hit to the European Union (EU) economy if there is a “no deal” Brexit.

Taoiseach Leo Varadkar proposed Wednesday night closing Irish airspace to its largest trading partner if Prime Minister Theresa May does not allow Irish fishermen unlimited access to UK waters.

When asked whether or not flights could operate between the UK and Ireland post-Brexit, Mr Varadkar said: “The situation at the moment is that the UK is part of the single European sky.

“If they leave the EU they are not, and that does mean if there was a no-deal hard Brexit next March, the planes would not fly and Britain would be an island in many ways.

According to the Irish Examiner, he added: “If they want their planes to fly over our skies, they would need to take that into account.

“You can’t have your cake and eat it. You can’t take back your waters and then expect to take back other people’s sky.”

If the Irish Prime Minister says British planes could not fly through Irish airspace if we leave EU without a surrender treaty, sorry ‘Deal’, then as a matter of principle he would be not able to accept our gas through our pipelines either, surely? https://t.co/jTrSDWLH16 — Gerard Batten MEP (@GerardBattenMEP) July 20, 2018

UKIP leader Gerard Batten hit back on Twitter by highlighting potential retaliation from the UK. He wrote:

“If the Irish Prime Minister says British planes could not fly through Irish airspace if we leave EU without a surrender treaty, sorry ‘Deal’, then as a matter of principle he would be not able to accept our gas through our pipelines either, surely?”

Leading Tory Brexiteer MP Jacob Rees-Mogg blasted: “Air traffic control continued between Russia and the Ukraine after Russia invaded the Crimea so this idea is just silly.

“On the other hand most flights from the EU to America pass through our air traffic control so this rather lightweight Irish gentleman is proposing an absurd act of a masochistic nature.

“His words are those of an airhead.”

A key promise of Brexiteers in the referendum campaign was leaving the European Union’s (EU) Common Fisheries Policy, described by former UKIP leader Nigel Farage as a litmus test for Brexit.

Theresa May made a concession to the EU and handed them two years of continued access to UK waters after Brexit, but Tory environment secretary Michael Gove promised this month to eventually pull out of the fisheries policy and give a “fairer share” to the UK.