Rishi Sunak risks inflaming his row with Ireland over the return of asylum seekers after he accused the Irish government of “cherry picking” international agreements.
The prime minister said his administration was seeking “urgent clarification” there would be no new checkpoints at or near the border with Northern Ireland as tensions between London and Dublin escalate.
Ireland has hit out at what it says is a high number of recent arrivals coming from the UK.
It has said it will redeploy 100 police officers to deal with the problem, although it has denied that these will be used along the border, the scene of much violence during the Troubles.
The Irish cabinet has also approved a plan to start returns to the UK, something Mr Sunak says the UK will not accept.
An open border is a key tenet of the Good Friday Agreement, which brought the Troubles to an end.
Mr Sunak told MPs there could no be “cherry-picking” of international agreements from the Irish government.
He said the UK had “made commitments to avoid a hard border on the island of Ireland and … the Irish government must uphold its promises too.
“We can’t have cherry-picking of important international agreements and so the Secretary of State is seeking urgent clarification that there will be no disruption or police checkpoints at or near the border.”
He added: “And I can confirm that the United Kingdom has no legal obligation to accept returns of illegal migrants from Ireland.”
He claimed his administration’s “robust approach to illegal migration” – his controversial plan to deport asylum seekers to Rwanda – was proving a deterrent to migrants coming to Britain.
But he added “The answer is not sending police to villages in Donegal (near the border with Northern Ireland). It’s to work with us in partnership to strengthen our external borders all around the Common Travel Area that we share.”
The Irish Department of Justice has refused to publish an operational arrangement it says provides for returning asylum seekers to the UK.
No 10 insists it is “non-binding” and said that Ireland has not returned anyone to the UK since Brexit.
On Sunday Irish premier Simon Harris said Ireland would not “provide a loophole” for other countries’ migration “challenges”.
Mr Sunak has said the UK is “not interested” in any returns deal if the EU does not allow the UK to deport asylum seekers back to France.
