Ireland and Britain will “beef up” co-operation after Brexit, the Irish Taoiseach said.

UK Prime Minister Boris Johnson repeated that fresh checks would not be imposed on goods travelling from Great Britain to Northern Ireland, except where they were destined for the Republic of Ireland if no EU trade deal can be struck.

The post-Brexit customs solution is designed to prevent a hard land border between Northern Ireland and the Republic.

It has been characterised by its unionist opponents as a de-facto border in the Irish Sea.

Mr Johnson said: “The only circumstances in which you could imagine the need for checks coming from GB to NI – as I have explained before – is if those goods were going on in to Ireland, and we had not secured, which I hope and am confident we will, a zero-tariff, zero-quota agreement with our friends and partners in the EU.”

Organisations allowing co-operation between Northern Ireland, the Republic and Great Britain are set to be reactivated following last week’s Stormont deal.

Mr Varadkar said: “We are going to beef up and deepen co-operation between Britain and Ireland in the interests of everyone who lives on these islands.”

Mr Johnson acknowledged there could be checks on goods crossing the Irish Sea that were destined for the Republic of Ireland as a result of Brexit.

He insisted that a deal with Brussels could mean they were not necessary.

“I cannot see any circumstances whatever in which there would be any need for checks on goods going from Northern Ireland to GB.”