The Taoiseach has said that whoever takes over as the new British Prime Minister in the coming weeks needs to understand that the European Union means what it says when it says the Brexit Withdrawal Agreement will not be reopened.
Leo Varadkar was speaking at a meeting of the British Irish Council in Manchester.
He said the current leadership race was an internal matter for the Conservative Party, but the EU had been consistent in its view that the agreement has been reached between the British government and the EU and will not be reopened.
The Taoiseach said there was scope for negotiation on the political declaration which accompanies the deal.
Both candidates for the Tory leadership have suggested they would seek a renegotiation of the Withdrawal Agreement to try to avoid leaving the EU without a deal.
David Lidington, the de facto British deputy Prime Minister, said he had always taken the EU at its word when it said the deal would not be reopened and that the only changes possible would be to the political declaration.
The Taoiseach also rejected the suggestion by DUP leader Arlene Foster that the Irish Government stance on Brexit had damaged relations north and south of the border.
Mr Varadkar said any damage in relations had come from Brexit itself, rather than the Irish Government, and underlined the economic damage a no-deal Brexit could potentially do to Ireland.
The British Irish Council was established under the Good Friday Agreement and meets twice a year with representatives of the Irish and British governments as well as representatives from the devolved administrations of Scotland and Wales.
Today's meeting was dominated by the issue of Brexit amid the Conservative Party leadership contest.
Other key issues such as the political situation in Northern Ireland were also due to be discussed.
Mr Varadkar was joined by Scotland's First Minister Nicola Sturgeon and representatives from the devolved administrations of Wales and the Channel Islands for the 32nd British Irish Council Summit.
He held talks with Scottish First Minister Nicola Sturgeon where the recent Rockall fishing dispute between Scotland and Ireland was discussed.
He will also take part in an Enterprise Ireland round table of leading Irish companies involved in growing their business in the Manchester region, and visit a Sisk development in the city.