Taoiseach Leo Varadkar has said he would like to see “real engagement” from Britain in negotiations with the EU starting on Monday on how to avoid a hard border in Ireland after Brexit.

EU and UK officials meet on Monday in Brussels to discuss how to maintain an open Irish Border.

Speaking at the end of an EU summit, Mr Varadkar said “the onus was on them” to make proposals to avoid the “backstop” option that would effectively keep Northern Ireland under EU rules if there was no deal on Brexit.

Talks begin a week after the UK conceded that the backstop should be in the legal text of the agreement. London initially rejected the option when the EU published the draft withdrawal treaty covering Brexit last month.

While both sides agree that there needs to be a default no-hard-border backstop in the absence of any other solution, there is no agreement around either that option or another solution for the Border question.

On the table “What I would like to see from them next week in the discussions is real engagement, and they’ve agreed to engage on the text that we have put on the table, so I would like to see them engaging with that essentially.”

The Taoiseach signalled this week that the Border issue may not be resolved until the overall withdrawal treaty is agreed by the October deadline.

His remarks sparked criticism from Fianna Fáil’s Brexit spokesman Stephen Donnelly that the Government was “losing leverage”.

European Council president Donald Tusk pushed an earlier deadline on the Border, telling reporters: “Leaders will assess in June if the Irish question has been resolved, and how to go about a common declaration on our future.”

The Taoiseach said the Government would “certainly like to see most or all” of the Brexit protocol on Ireland agreed by the next EU summit in June.

He rejected Mr Donnelly’s view that the Irish had “lost leverage” with the agreement that London would have a 21-month transition period to avoid a disorderly Brexit after its departure from the EU in March 2019.

Transition period “Some people may think that the United Kingdom has banked that transition period. It is the case though that nothing is agreed until everything is agreed, and that can really only happen in October,” he said.

On growing divisions with Fianna Fáil and other Opposition parties over the Brexit negotiations, Mr Varadkar said he felt that there had been a “change in tone and a change in temperature” in recent months, and that Fianna Fáil had moved from “constructive opposition” to “opposition for opposition’s sake”.

British prime minister Theresa May said there was a “new dynamic now” and a “spirit of co-operation” in the Brexit negotiations.