The UK government has demanded that executives who supplied combustible cladding to Grenfell Tower “step up to the plate” after their refusal to give evidence to the public inquiry into the disaster provoked anger among the bereaved and survivors. On Sunday, Stephen Greenhalgh, the building safety minister, escalated a legal and diplomatic dispute over the position taken by three current and former executives at the French division of the US company Arconic. He told them to stop hiding behind an arcane French law. Arconic made the polyethylene-filled aluminium composite panels that were the main cause of the spread of the fire, which killed 72 people. The witnesses, based in France and Germany, are wanted by the inquiry to account for their role in manufacturing, testing and marketing the cladding, which is now banned on high rise homes in the UK. The former executives Claude Wehrle and Peter Froehlich, alongside Gwenaëlle Derrendinger, a current employee, are citing the rarely used 53-year-old French blocking statute and are refusing to attend six days of cross-examination due this month. Two UK-based Arconic witnesses will give evidence. In 2009, Wehrle shared with Arconic colleagues images of a burning tower fitted with similar panels to those it sold to Grenfell “to show you how dangerous PE [polyethylene] can be when it comes to architecture”. In 2015, he emailed colleagues: “PE is dangerous on facades, and everything should be transferred to fire-resistant as a matter of urgency.” Greenhalgh spoke out on Twitter after a months-long deadlock in which the witnesses have resisted calls by the inquiry to “do the right thing” and ignored warnings that non-attendance runs the risk of “adverse inference and criticism”. The inquiry has been communicating directly with the French government via the Foreign, Commonwealth and Development Office to try to get them to appear. Greenhalgh tweeted: “Time for these ⁦@arconic⁩ executives to step up to the plate + appear before the #GrenfellTower Inquiry rather than hide behind the 1968 French Blocking Statute.” In November, the inquiry said it would “empty-chair” the trio if they did not attend. It would set out email evidence relating to their actions and frame the questions they needed to answer. A fourth Arconic executive, Claude Schmidt, has said he will only give evidence if the inquiry accepts “certain conditions”, which have not been made public. The inquiry said last month they were largely unacceptable. Schmidt still works for Arconic. Grenfell United, the survivors and families group, has said “there is no way Arconic staff should be dictating terms about what they are asked or not asked”. The row over the witnesses’ appearance has been rumbling since before November, when the inquiry publicly revealed their refusal. Counsel to the inquiry, Richard Millett QC, said “neither Arconic nor any of those witnesses has provided any evidence that there is a real risk of prosecution under the French blocking statute”. Last month, the bereaved and survivors mounted a protest outside the French embassy in London, and the French government said it did not believe the blocking statute applies. Arconic Architectural Products (AAP) said it “continues to fully cooperate with the inquiry”. “The individuals who have declined to participate … have taken the advice of separate counsel and AAP does not have any influence on those decisions,” a spokesperson said. “The three witnesses who are represented by the company’s counsel are prepared to provide evidence, including Claude Schmidt.” The inquiry is due to resume on 11 January.