Rishi Sunak has been warned he will be breaking European human rights law if his Government ignores emergency court orders intended to stop asylum seekers being sent to Rwanda.

The Prime Minister has repeatedly vowed not to let “foreign courts” block the plan to send some migrants on a one-way trip to the African nation.

The Safety of Rwanda (Asylum and Immigration) Bill going through Parliament states that it is up to ministers to decide whether or not to comply with interim rulings issued by judges in the European Court of Human Rights.

But the Strasbourg court’s president, Siofra O’Leary, said “there is a clear legal obligation” under the European Convention on Human Rights (ECHR) for states to comply with the so-called Rule 39 interim measures.

Downing Street insisted the Rwanda legislation complied with international law and suggested it would also mean that Strasbourg had no need to intervene.

A Rule 39 measure – branded a “pyjama injunction” by critics because it can be issued outside normal court hours – contributed to the 2022 grounding of the first flight intended to take asylum seekers to Rwanda under the Government’s controversial scheme.

There is a clear legal obligation under the Convention for states to comply with Rule 39 measures

The new legislation going through Parliament seeks to address the legal challenges which have dogged the scheme and states that ministers have the power to ignore such rulings.

But Ms O’Leary told a press conference: “There is a clear legal obligation under the Convention for states to comply with Rule 39 measures.“

She said the interim measures are only issued “in exceptional circumstances where there is a real and imminent risk of irreparable harm”.

Countries which have failed to comply with Rule 39 indications have previously been found to have violated obligations under Article 34 of the ECHR, which gives the right for individuals to apply to the court once domestic legal routes have been exhausted.

I know there’s a very healthy debate in the United Kingdom relating to the content of the Bill

Senior judge Ms O’Leary said the UK “has always complied with Rule 39 measures”, except in one very particular case, and has “publicly declared the need for other states to comply with Rule 39 indications” – including urging Vladimir Putin’s Russia to abide by a 2021 measure in relation to the release of opposition leader Alexei Navalny.

The Strasbourg court president would not be drawn on the Safety of Rwanda Bill while it goes through the parliamentary process.

But she said: “I know there’s a very healthy debate in the United Kingdom relating to the content of the Bill.

“It’s a country which is blessed with many, many international legal experts and a very active civil society. So I am sure that all of those issues can be fully examined.”

In the Rwanda case in June 2022, the interim measure blocking an Iraqi asylum seeker being sent to the African state was granted just hours before the flight was due to take off.

The Prime Minister has been clear repeatedly that we will not let a foreign court block flights from taking off

Ms O’Leary said Rule 39 measures are almost always sought in “situations of urgency, if not extreme urgency, and the nature of the urgency or the degree of urgency is something which respondent governments control”.

The interim injunction powers are rarely used – in 2023 13 requests were refused, and just one interim measure was granted.

The Rule 39 process is currently being reformed and since December 2023 the duty judge issuing an interim measure will be identified, addressing one of the criticisms of the situation in the Rwanda case.

The Prime Minister’s official spokesman said: “We’ve set out our case very clearly.

“I think, firstly, we are confident our legislation is compliant with our international obligations. We’re clear the Bill and the treaty address the Supreme Court’s concerns. There should be no need for Strasbourg to intervene to block flights in the way they did in 2022.

I think it would be bizarre to draw any comparison between Russia’s cruel treatment of Alexei Navalny ... and our plan to protect and deter vulnerable migrants from making perilous crossings across the Channel

“We’ve also drafted the Bill to give ministers the power not to comply with those rulings if necessary. And obviously every case is assessed on its individual facts, but the Prime Minister has been clear repeatedly that we will not let a foreign court block flights from taking off.”

The spokesman added: “I think it would be bizarre to draw any comparison between Russia’s cruel treatment of Alexei Navalny, who was a victim of an attempted assassination attempt, and our plan to protect and deter vulnerable migrants from making perilous crossings across the Channel.”

Meanwhile, the head of the United Nations’ refugee agency also criticised the Government’s approach.

UN High Commissioner for Refugees Filippo Grandi told the BBC that some countries with “more resources” were devising “systems with which they would abdicate responsibilities they have to asylum seekers and shift these responsibilities to other states”.

“This is contrary to the basic principles of refugee protection,” he said.