The Love Actually actor stated that the government’s policies do not reflect “the character of our country” and added, “We cannot become fortresses. “Dame Emma Thompson denounced the plan to deport migrants to Rwanda as “mind-bogglingly insane and inhumane.”

She suggested that it was unrealistic to attempt to “become fortresses” in light of the likelihood that climate change and war will make migration a more pressing issue.

Her remarks regarding the Rwanda programme echo those of a number of activists and politicians, including some Conservatives.

Former Treasury minister Jesse Norman, who announced earlier this week that he was dropping his support for Boris Johnson ahead of a bruising vote of confidence, branded the Rwanda strategy as “ugly, possibly unproductive, and of questionable legality.”

The plan to deport illegal immigrants to Rwanda is intended to discourage anybody from attempting the risky crossing of the English Channel in small boats.

It has been called as “cruel and ugly” by critics, and the Archbishop of Canterbury has stated that the proposal is “contrary to God’s nature.”

However, the prime minister asserts that it is “the morally correct course of action.”

Dame Emma, who has a Rwandan adopted son, discussed the policy in an interview with Sky News political editor Beth Rigby prior to the publication of her new film Good Luck to You, Leo Grande.

She stated that she did not believe Britain was doing enough for all refugees.

“The Rwanda plan is ludicrous and heartless,” she added.

We are displaying a callousness in governance that I do not believe reflects the soul of this country or the character of its people.

The actress acknowledged that some migrants may feel that the kind of welcome afforded to white Ukrainians seeking asylum was not extended to Syrians escaping violence in the past.

She then added: “Simultaneously, there has been a tremendous outpouring of compassion from the British people.

“People in this country have all wanted to contribute, but have been greatly impeded from doing so by government systems and a variety of internal obstacles including things like bank accounts – our civil society is not being helped to rise to the occasion.

“The movement of people, not just due to war but also due to climate change, will be one of the greatest challenges of our time and the 21st century in general.

“We must begin to comprehend how people must relocate, and we must embrace this reality.

“We can no longer become fortresses or erect barriers. It is not plausible.”

When unveiling the programme earlier this year, the prime minister predicted that it would be contested by “a powerful army of politically-motivated lawyers.”

The first flight from the United Kingdom to Rwanda under the plan is due to depart next Tuesday, but 90 migrants have already filed legal challenges.