Hong Kong education authorities have hit back at a leading teachers’ union after it said changes made to textbooks for the controversial liberal studies subject under a voluntary screening scheme were unprofessional and involved political censorship. The Education Bureau on Wednesday condemned and expressed “deep regret” at allegations by the pro-democracy Professional Teachers’ Union (PTU) and said the vetting of textbooks aimed to “help students develop positive values”. Six publishers, which account for most of the liberal studies textbook market, joined a voluntary consultancy service introduced by the bureau last year, with the first batch of vetted books expected to be in use this September. Liberal studies textbooks did not require the bureau’s approval, unlike those for other core subjects. Publishers told teachers this week of the changes, which included amendments such as the removal of the phrase “separation of powers” and criticism of the mainland Chinese government. Several political cartoons were replaced while the definition of civil disobedience also emphasised the possible criminal consequences for participants. Implemented as a compulsory subject for senior secondary pupils in 2009 with the aim of strengthening critical thinking and raising awareness of current issues, liberal studies has come under attack in recent years, with pro-establishment figures saying it was one of the reasons behind youths becoming radicalised and that some teachers promoted a political agenda during class. In a statement on Wednesday, the 100,000-strong PTU lashed out at the bureau over the changes, accusing it of practising “political censorship” by asking publishers to remove sensitive content and “downplaying or twisting the reality” of certain issues. The union also said the bureau’s advisory scheme had “severely damaged the original goals” of setting up the subject. “The bureau’s vetting scheme has not only created chaos among publishers, frontline teachers, parents and students, the liberal studies books have also been edited under political censorship, which is clearly beyond professionalism,” the statement said. “We condemn [the bureau’s] acts, and urge that the bureau would stop reintroducing such a ‘professional consultancy service’ next year.” Within hours, the bureau responded with a strongly worded statement, calling the union’s accusations “totally unfounded, based on twisted facts and deliberately smearing the service”. It said the changes, including to texts, illustrations and cartoons, were made by publishers themselves after the bureau gave them advice. “The publishers voluntarily participated in the professional consultancy service and refined the textbooks, with a view to sieving out the inaccurate parts from the rest. This is for ensuring that the information is correct, based on facts, keeping abreast of the times,” a bureau spokesman said. “[The refined textbooks are also] clear and easy to understand, while avoiding the possibility of exaggeration, inaccuracy or misleading students’ understanding. These would help students construct knowledge and develop positive values.” He added: “The [bureau] strongly condemns the PTU’s attempts to judge the bureau’s service through a politically coloured lens and politicise the professional work of education again.” The bureau said a team of inspectors, university academics and education professionals had sat in the team which gave publishers advice. Meanwhile, the bureau’s statement noted concerns had been raised over whether the textbooks, even after undergoing vetting, could still be in possible violation of the city’s new national security law , which was implemented on June 30 after the initial screening took place. It said publishers had the responsibility to make sure that the contents did not violate the law. The legislation targets acts of secession, subversion, terrorism and collusion with foreign forces. Secondary school principal Tang Fei, of the pro-establishment Hong Kong Federation of Education Workers, believed the bureau should take the lead to scrutinise the textbooks again before the new school year began in September. “Publishers would be more relieved, while teachers would also feel the same. The bureau should take up that responsibility as publishers would find it difficult to decide which content might violate the city laws,” he said.