Clarence House has insisted the Prince of Wales “remains politically neutral”, despite reported private comments criticising the government’s controversial policy of deporting asylum seekers to Rwanda.

A union challenging the policy said it hopes it can win an appeal to stop the first flight taking off this week.

A High Court ruling on Friday paved the way for a flight to the east African country to go ahead on Tuesday but an appeal against that decision is due to be heard on Monday.

The immigration policy - aimed at preventing people in small boats crossing the Channel and landing on the Kent coast - has come in for criticism from various groups, including Archbishop of Canterbury Justin Welby.

Last week the Prince of Wales was said to be “more than disappointed” by it, amid reports that he privately described the move to send migrants to Rwanda as “appalling”.

GB News presenter and former UKIP leader Nigel Farage is among those to have criticised the Prince's reported intervention.

Mr Farage tweeted yesterday: "Unless Prince Charles wants to destroy the monarchy he had better shut up fast."

The Times reported that the Prince was said to be frustrated at Boris Johnson’s asylum policy as he prepares to represent the Queen at the Commonwealth Heads of Government meeting in Rwanda later this month.

The paper said a source reportedly heard Charles, 73, expressing his opposition, telling the newspaper: "He said he was more than disappointed at the policy.

"He said he thinks the government’s whole approach is appalling. It was clear he was not impressed with the government’s direction of travel."

The boss of the Public and Commercial Services union (PCS), which represents more than 80% of Border Force staff, said the “legality of these proposals” must be tested, but added there is also a need to debate “the morality and lack of humanity that the Government is demonstrating” with its approach.

Up to 130 people have been notified they could be removed, and on Friday the court in London heard that 31 people were due on the first flight, with the Home Office planning to schedule more this year.

The first claim against the policy was brought by lawyers on behalf of some asylum seekers alongside the PCS, as well as groups Care4Calais and Detention Action, which are challenging the policy on behalf of everyone affected.

Mr Justice Swift on Friday ruled against granting a temporary block to the policy until a full hearing next month, but granted the claimants permission to appeal against his decision, suggesting Court of Appeal judges would hear the case on Monday.

PCS general secretary Mark Serwotka told Sky’s Sophy Ridge On Sunday programme: “We hope we win tomorrow in the Court of Appeal to stop the flight (on Tuesday).

“But, of course, the legality of these proposals will only be tested out at the full court hearing in July.

“We’re absolutely confident that in July, in line with what the UNHCR (UN Refugee Agency) said very graphically in court, we believe these proposals will be found to be unlawful.”

He said Home Secretary Priti Patel would not ask civil servants to carry out the policy before its legality had been tested in court if she “had any respect, not just for the desperate people who come to this country, but for the workers she employs”.

Northern Ireland Secretary Brandon Lewis defended the Government’s policy, saying it aims to “break” the “business model” of people smugglers.

He said: “The reality is this is a policy that is going to deliver to ensure that modern slavery and these people smugglers know that their criminal methods will be broken down, and saying to people around the world ‘if you are a refugee, if you are an asylum seeker, if you are a legal migrant coming to this country, we want to give you the support to properly help you be part of the UK economy, part of the UK way of life, which is what you want’, and that’s right.”

He said it would not be “appropriate” to comment on “rumoured” criticism from Charles.

A Clarence House spokesman has insisted the Prince of Wales “remains politically neutral”, adding that “matters of policy are decisions for Government”.

Small boat crossings have continued over the last four years with people landing on beaches in Kent, or being rescued at sea and initially being brought to Dover.

This year, more than 10,000 asylum seekers crossed the Channel in small boats. More than 28,500 asylum seekers made the crossing in all 2021, more than three times the number doing so the previous year.

Previously, the Home Office said: “Our world-leading partnership with Rwanda is a key part of our strategy to overhaul the broken asylum system.

"We have been clear from the start that we expected legal challenges, however we are determined to deliver this new partnership.

“We have now issued formal directions to the first group of people due to be relocated to Rwanda later this month.

"This marks a critical step towards operationalising the policy, which fully complies with international and national law.”