It is too early to jump to conclusions about the impact of the Rwanda plan, Downing Street has said, after the Irish Government claimed it was causing an influx of migrants into the Republic.

Deputy Irish premier Micheal Martin said the policy is already impacting on Ireland, as asylum seekers are now fearful of staying in the UK.

Ministers plan to send asylum seekers coming to the UK on a one-way flight to the east African nation, with the aim of deterring others from making the dangerous English Channel crossing.

The legislation ensuring the plan is legally sound, the Safety of Rwanda (Asylum and Immigration) Act, cleared its passage through Parliament this week and was signed into law on Thursday.

Mr Martin, who also serves as Ireland’s foreign affairs minister, said migrants are crossing from Northern Ireland into the Republic to seek safety from deportation to Rwanda.

He told reporters in Dublin on Friday that he did not agree with the policy, adding: “Clearly, we’ve had an increase in the numbers coming UK into Northern Ireland into the Republic. And it’s fairly obvious that a Rwanda policy, if you’re a person in a given situation in the UK and well, then you don’t want to go to Rwanda – not that anybody has gone yet, I hasten to add.

“So I think it’s a fair comment of mine. There are many other issues – it’s not in any way trying to blame anything or anything like that.”

The Tanaiste continued: “Migration is happening all over Europe. It’s a national phenomenon. Part of the EU asylum pact is that we develop proper policies so that we can return people who’ve already been granted asylum in one country, that if they come to Ireland, they can be returned to the country where they were granted asylum in the first place. And the United Kingdom are outside of European Union.

“But it hasn’t worked in the UK in terms of the numbers coming into the UK.

“I’ve watched governments all over Europe making big commitments that they are going to stop the boats, they’re going to stop the numbers migrating. Brexit was meant to slow down migration into the United Kingdom, and migration into United Kingdom has grown exponentially, increased exponentially, since Brexit.

“It’s different migrants coming in, compared to pre-Brexit time. But I think it all goes back to what’s happening across the world. There is phenomenal movements of people who are fleeing war and devastation.”

A No 10 spokeswoman rebuffed claims the plan was already influencing movements into Ireland.

“It is too early to jump to specific conclusions about the impact of the Act and treaty in terms of migrant behaviour,” she said.

“Of course, we will monitor this very closely and we already work very closely as you would expect with the Irish government, including on matters relating to asylum.

“But of course, the intention behind the Act is to have it serve as a deterrent and that is why we are working to get flights off the ground as swiftly as possible.”

Irish ministers earlier this week suggested there had been a rise in the number of migrants crossing the land border between Northern Ireland and the Republic.

Justice minister Helen McEntee told a committee of the Irish Parliament the number was now “higher than 80%” crossing from Northern Ireland.

As in the UK, migration has become a hot button issue among some voters in Ireland, with worries about a housing shortage coinciding with a rise in the number of migrants accepted.

Mr Martin’s comments follow on the heels of French president Emmanuel Macron’s criticism of migration policies that involve sending people to African countries as “a betrayal of our values”.

Scheduling of flights to Rwanda could take between 10 and 12 weeks, Prime Minister Rishi Sunak has said, meaning the first will not begin until summer at the earliest.

Home Secretary James Cleverly has said there will be “multiple flights per month, through the summer and beyond” once they eventually get off the ground.

While scheduling flights is likely to take some time because of the procedures officials must follow, the plan could face further delays if the Government is taken to court again.

Opponents of the multimillion-pound plan, and migrants who are told they are to be sent to Rwanda, could issue legal challenges in a bid to stop the flights.

But it is unclear whether any further legal action would succeed in light of the new laws.