A whistleblower who was sacked for highlighting Britain’s chaotic response to the fall of Kabul has expressed frustration at government attempts to have her legal challenge against her dismissal held in private. Josie Stewart, a senior official, was fired from the Foreign, Commonwealth and Development Office (FCDO) for giving an anonymous interview to the BBC about the failures in the handling of the Afghan withdrawal. The Guardian revealed she is taking her treatment to employment tribunal to test legal protections for whistleblowers amid concerns there is insufficient protection for civil servants who disclose sensitive information in the public interest. But the government is trying to ensure that all or part of these proceedings are held in private on national security grounds, under rule 94 of the employment tribunal rules. Her case is due to be heard in September, but this week Stewart and her lawyers attended a preliminary hearing before a judge, Andrew Glennie, to decide whether the full hearing would be heard in private. The preliminary hearing was held in private on Wednesday. The Guardian tried to attend but was refused entry. In an update to her supporters on the CrowdJustice website, Stewart said the proceedings were “infuriating” in part because she could not disclose details of what was said. She wrote: “This hearing was listed in order to hear and decide upon [the] government’s rule 94 (national security proceedings) application. As the hearing was held in private, frustratingly I am not able to share anything that was said. A Guardian reporter whom I met at reception … who had turned up to cover the hearing, was turned away.” She added: “What I can say is that we will receive the judge’s decision and reasons on 18 May. Also that I found today intense, emotional, infuriating and motivating. And that my legal team are truly incredible: it was a privilege to witness them at work.” “There are truly important issues at stake, which my lawyers are fighting not only on my behalf. They deserve my and our support.” Legal sources said the government’s use of rule 94 was an attempt to limit media coverage of the case and the FCDO’s embarrassment at what Stewart revealed about the withdrawal from Kabul. At the time the then foreign secretary, Dominic Raab, was criticised for staying on holiday when the Taliban retook Afghanistan. Stewart, who worked for the Foreign Office for seven years including two at the British embassy in Kabul, said her former colleagues felt their role was to protect ministers, some of whom were only interested in “looking good”. Speaking to the Guardian in February she said Sir Philip Barton, the FCDO’s permanent secretary, was too willing to do the bidding of his political masters. “I think he has potentially lost sight of the importance of his leadership role in trying to fix that broken system rather than cementing some of its problems,” she said. Stewart, who now works for now works for the anti-corruption campaign Transparency International, also explained why she is taking action. She said: “If the law is not tested and used then I don’t know how much it actually means as potential whistleblowers don’t know which side of the line it is going to fall. Is what they’re going to do likely to be legally protected or not? If they don’t know then I’m not sure how meaningful the fact the law exists is.” The FCDO believes Stewart misrepresented the withdrawal from Afghanistan. A spokesperson said: “We are rightly proud of our staff who worked tirelessly to evacuate more than 15,000 people from Afghanistan within a fortnight. This was the biggest mission of its kind in generations and the second largest evacuation carried out by any country. We implemented lessons learnt from the Afghanistan response in our response to Russia’s invasion of Ukraine.”