Irish premier Simon Harris has said Ireland will not “provide a loophole for anybody else’s migration challenges”, while the UK Government rejected the Republic’s bid to return asylum seekers in a deepening of the diplomatic spat.

Mr Harris was speaking after UK Prime Minister Rishi Sunak said claims that the UK’s Rwanda plan is causing an increase in migration to Ireland shows its deterrent effect is working.

The Irish Government has said there has been a shift in migration patterns into Ireland in recent months and the number of migrants crossing from Northern Ireland is now “higher than 80%”.

Legislation is to be introduced next week in response to an Irish High Court ruling that Ireland’s designation of the UK as a “safe third country” for returning asylum seekers, in the context of the Rwanda plan, is contrary to EU law.

The UK’s Rwanda plan aims to send asylum seekers to the east African nation to deter others from crossing the English Channel on small boats.

Labour’s shadow immigration minister Stephen Kinnock said new data indicates Mr Sunak’s plan is not working.

Newly released Home Office figures show more than 7,000 people arrived by small boats before the end of April.

“This is the blunt reality behind all of Rishi Sunak’s empty boasts; more people have arrived by small boats so far this year than ever before and more people are having to be rescued,” Mr Kinnock said.

“What will it take for Rishi Sunak to wake up and realise that his plan is not working?”

Asked on Sunday whether the increase in asylum seekers travelling from the UK to Ireland suggested the Rwanda policy was working, Mr Harris said: “I’m not going to comment on whether the British migration policy is working, that’s a matter for him (Mr Sunak) to put to the British people.

“Every country is entitled to have its own migration policy, but I certainly don’t intend to allow anybody else’s migration policy to affect the integrity of our own one.

“This country will not in any way, shape or form provide a loophole for anybody else’s migration challenges. That’s very clear.

“Other countries can decide how they wish to advance migration. From an Irish perspective, we intend to have a firm rules-based system where rules are in place, where rules are in force, where rules are seen to be enforced.

“It is a statement of fact that there was a returns agreement in place between Ireland and Britain, and there was a High Court decision in the month of March in relation to that.

“My colleague, the Minister for Justice, will now bring forward legislative proposals to Cabinet on Tuesday that will seek to put in place a new returns policy. We’re going to await the full details of that but it’s one which will effectively allow, again, people to be returned to the United Kingdom. And I think that’s quite appropriate. It was always the intention.”

But the UK Government rejected any bid by Ireland to return asylum seekers unless France agrees to do the same.

A Government source said: “We won’t accept any asylum returns from the EU via Ireland until the EU accepts that we can send them back to France.

“We are fully focused on operationalising our Rwanda scheme and will continue working with the French to stop the boats from crossing the Channel.”

Irish Justice Minister Helen McEntee had been due to meet Home Secretary James Cleverly on Monday, but a note was sent out late on Sunday to say the meeting had been postponed.

Meanwhile, Northern Ireland First Minister Michelle O’Neill called for a “thought-out” response between the British and Irish governments.

The Sinn Fein vice president said Mr Harris, Ms McEntee and Irish deputy premier Micheal Martin had not been in contact with her about planned legislation on asylum seekers arriving in Ireland from the UK.

“I am the First Minister in the north and I have yet to hear from the Taoiseach or the Tanaiste or the Justice Minister,” she said in Dublin on Sunday morning.

“To me, that highlights, maybe even underlines, how disorganised they are in dealing with this issue.

“Policy responsibility for migration and immigration sits with the British Government. I’m aware that Helen McEntee is to meet James Cleverly over the course of the next 24 to 36 hours.

“There’s also a British-Irish intergovernmental conference this week – this is the forum in which these issues need to be addressed.

“This is the forum in which there should be a solution coming out the other end, but a thought-out solution, an actually considered solution, a human rights-compliant solution, and we look forward to (that) over the next couple of days.”

Ms O’Neill was speaking at a launch of the party’s local, European and Limerick mayoral election campaign in Dublin.

Sinn Fein leader Mary Lou McDonald, who was also at the event, said cross-border migration means Ireland should reject a newly revealed overhaul of EU laws on migration and asylum.

“I think the turn of events and the specific set of circumstances that we have to deal with on the island of Ireland actually argue against signing up to the EU migration pact lock, stock and barrel.

“Unlike other European jurisdictions, we have to deal with our next-door neighbour of Britain and we have to have the flexibility and the capacity to manage that.”