The UN's refugee agency warned the Home Office twice that its arrangement to send asylum seekers to Rwanda was unlawful, the High Court has heard.

The agency's lawyers distanced it from the policy amid claims the Home Office has misrepresented the UN's position.

It came as a legal challenge to stop the process got under way.

The government aims to discourage people crossing the English Channel to seek asylum by making it clear many cases will now be dealt with by Rwanda.

About 31 people have been told they may be on the first flight on Tuesday.

Just before the start of the hearing, it emerged at least three people have been told they will not now be put on that flight.

Home Office lawyers told the court the plan must not be stopped by legal challenges because it was in the public interest and also urged a judge to reject challenges on behalf of individual asylum seekers.

While their application is considered by the east African country they will be given accommodation and support and, if successful, will be able to remain in Rwanda with up to five years' access to education and support.

Those who fail in their asylum bids in Rwanda will be offered the chance to apply for visas under other immigration routes if they wish to remain in the country, but could still face deportation.

In practice, the policy is targeted at English Channel crossings, with more than 10,000 so far this year.

The case brought against the Home Office by a coalition of campaigners has two stages.

Firstly, the claimants want to block the removal to Rwanda of specific individuals who have been told they are leaving.

Secondly, they want to challenge the lawfulness of any such transfers to Rwanda.

Laura Dubinsky QC, representing the UN refugee agency, told the court "in light of inaccuracies" she wanted to clarify that it in no way endorsed the UK-Rwanda arrangement.

The UNHCR has responsibility for oversight of international refugee law and institutional expertise.

Ms Dubinksy said two meetings between the agency and the Home Office took place in April - one in UK, the other in Rwanda - at which concerns were raised.

"At those April meetings, capacity issues and specific recent incidents of refoulement were raised by UNHCR," she said.

Refoulement is the practice of forcibly returning refugees or asylum seekers to a country where they are liable to be subjected to persecution. It is illegal under international law.

She said the UNHCR had informed the Home Office that the risk of refugees being refouled by Rwanda meant the scheme was unlawful.

The lawyer added that the agency was concerned about the risk of "serious, irreparable harm" caused to refugees sent to Rwanda, emphasising the body "in no way endorses the UK-Rwandan arrangement".

Among the people informed they will be sent to Rwanda on Tuesday is an Iranian ex-police commander who fled the country after refusing to shoot protesters during anti-government demonstrations in 2019.

The former commander, who is not being named in order to protect his identity, was sentenced by an Iranian military court to almost five years in jail in Iran and fears being killed by Iranian agents if he is deported.

The man previously gave testimony to the UK-based Aban Tribunal investigating alleged Iranian atrocities during the unrest, which estimates say led to the deaths of between 300 and 1,500 people.

He has been held at Brook House detention centre near Gatwick Airport after arriving in the UK from Turkey in May, where he had been in hiding for over a year after fleeing Iran.

Last week the former commander was given malaria pills in preparation for his trip, but he refused to take them and claims to have told the officers: "You can only send my dead body to Rwanda".

They said removals under the terms of the deal with Rwanda were "intended to deter people from making dangerous journeys to the UK to claim asylum, which are facilitated by criminal smugglers, when they have already travelled through safe third countries".

They added: "In particular, but not exclusively, this is aimed at deterring arrivals by small boats."

And they said it was "striking" that the legal submissions of those seeking to stop the flights did not consider "the impact of any public interest factors".

Raza Husain QC, representing some of the claimants, also raised in court the UNHCR's concerns about shortcomings in the Rwanda asylum system.

He said the agency's concerns included evidence that applicants for refuge could be arbitrarily denied proper access to a hearing, a lawyer and an interpreter - and could even find themselves removed to countries that torture.

The UN had not been able to properly monitor the quality of decision-making in the country despite Home Secretary Priti Patel's claims that Rwanda was safe, he said.

Mr Husain continued: "These are concerns that have been communicated to the UK authorities and yet the secretary of state's position is that the UN is giving this plan a green light. That is a false claim.

"This is not the view of a very reputable NGO - it is the view of the UNHCR and it is entitled to very significant weight."

The lawyer added: "We are not on the ground in Rwanda, the secretary of state is not on the ground in Rwanda," he said, adding: "The UNHCR is. How could you possibly implement a removal when the UNHCR has said this?"

Mr Justice Swift told the court the judicial review of the entire policy was likely to be complete within six to eight weeks.