The most senior civil servant at the Home Office has conceded that officials should not have used the phrase “activist lawyers” in a promotional video posted on Twitter, although the tweet remains online. The post on Wednesday described the department’s efforts to deport people with no right to remain in the UK and attacked “activist lawyers” for frustrating the process, prompting a furious response from barristers and solicitors. Matthew Rycroft, the Home Office’s permanent secretary, said in response to a complaint that he had told his team the term should not be used again. On Thursday night, the Home Office confirmed that a charter flight that was due to depart to Spain carrying asylum seekers who arrived in the UK on small boats had been cancelled. Home Office sources said the reason for the cancellation was due to a high volume of legal challenges. While its statement on the cancellation did not make any reference to “activist lawyers” it suggests that without the last-minute challenges the flight could have gone ahead. Earlier, writing to Jonathan Portes, a professor of economics at King’s College London, Rycroft had said: “The general point the video is making is that our efforts to facilitate legitimate and legal returns are often frustrated by individuals and lawyers putting in last-minute claims. These claims are very often entirely without merit, but have the effect of timing out a return due to stringent Dublin regulations. “However, I agree that the phrase you quote should not have been used on an official government channel. I have made clear to the team that this post should not be used again from Home Office accounts or anywhere else by civil servants.” The Dublin regulation is an EU law that broadly determines which member state is responsible for the examination of an asylum application. The Guardian approached the Home Office for comment, which declined to issue a refreshed statement and instead pointed to a tweet sent by Portes in which an extract of Rycroft’s response was included. Referring to the cancelled charter flight, a Home Office spokesperson said: “The government’s efforts to facilitate entirely legitimate and legal returns of people who have entered the UK through illegal routes are too often frustrated by last-minute challenges submitted hours before a scheduled flight. These claims are very often baseless and entirely without merit, but are given full legal consideration, leading to removal being rescheduled.” Portes had written directly to Rycroft arguing that the video was not consistent with the Government Communications Service (GCS) “propriety guidance” stating that messages should “be objective and explanatory, not biased or polemical”, as well as “sensitive to tone and guard against perceived attacks on particular interests, organisations or individuals”. Portes told the Guardian: “One of the jobs of civil servants is to communicate government policy. But they’re not allowed to use polemical language like this or target a particular group. This was way over the line. The prompt reaction of the permanent secretary is very welcome. I hope comms teams across Whitehall take note.” Lawyers condemned the video. Simon Davis, the president of the Law Society, which represents solicitors in England and Wales, said: “Attacks on the integrity of the legal profession undermine the rule of law. Solicitors advise their clients on their rights under the laws created by parliament. To describe lawyers who are upholding the law as ‘activist lawyers’ is misleading and dangerous.” Toufique Hossain, director of public law at Duncan Lewis, one of the “activist lawyers” the Home Office is referring to, demanded an apology from the Home Office. “In the light of the senior Home Office official accepting that it as wrong for the Home Office to use this term we would like an apology from Priti Patel. The cancellation of today’s charter flight shows that lawyers simply made legal representations. It was not us who forced the Home Office to cancel today’s charter flight. They took that decision themselves.” Amanda Pinto QC, the chair of the Bar Council, which represents all barristers in England and Wales, said: “Irresponsible, misleading communications from the government around the job that lawyers do in the public interest are extremely damaging to our society. “Legal professionals who apply the law and follow parliament’s express intention are not ‘activists’. They are merely doing their jobs, enabling people to exercise their statutory rights and defend themselves against those in power. Without those lawyers, our system would crumble.” David Lammy, the shadow justice secretary, said: “The Home Office’s misleading attack on solicitors who represent migrants is a deeply troubling attack on the rule of law. “The British legal system is respected around the world because of its reputation for fairness and independence. We should be proud that everyone who needs it is entitled to legal representation. “The Home Office should recognise its misjudgment by deleting the video.” Mark Serwotka, the general secretary of the PCS union, which represents civil servants, said the video was “a callous and inaccurate portrayal of a complicated issue which needs compassionate and calm discussion. People fleeing persecution have the right to seek asylum in the UK, and they have the right to be treated with dignity and humanity. “To use a graphics similar to Dad’s Army and equating that with migrants fleeing war and famine is politically and morally repugnant. “Home Office staff do an important job often in very difficult circumstances. And the last thing they need is the home secretary [Priti Patel] playing crude political games.”