The editorial board and dozens of journalists at Hungary’s biggest independent news outlet have resigned, two days after its editor-in-chief was fired amid claims of political interference.

More than 70 of roughly 90 editorial staff at index.hu, including all the desk editors, walked out of the newsroom on Friday after submitting their resignations in the wake of Szabolcs Dull’s dismissal earlier this week.

“A red line was crossed,” said deputy editor Veronika Munk, of the decision to resign.

The departing journalists published an open letter on the outlet’s website in Hungarian and English. “The editorial board deemed that the conditions for independent operation are no longer in place and have initiated the termination of their employment,” it said.

Munk, who has worked for the outlet for 18 years since joining as an intern while still a student, said many journalists were in tears as they left the newsroom for the last time on Friday.

Index was considered the last major independent outlet in Hungary, which is ranked the second worst country in the EU for media freedom by Reporters without Borders. During the past decade of rule by the far-right prime minister, Viktor Orbán, the media landscape has gradually contracted, as numerous outlets were bought out by pro-government figures or closed down.

Speaking on a visit to Portugal on Friday, Hungary’s foreign minister, Péter Szijjártó, said claims that government interference was behind the turmoil at Index were “untrue accusations”, while the company’s chief executive László Bodolai has insisted that there is no external interference in the outlet’s editorial line.

Munk said she had asked Bodolai to reinstate Dull in a number of meetings in recent days. “He repeatedly said no. He said it’s a personal decision but I don’t think it’s the real reason,” she said.

A pro-government businessman acquired a stake in Index’s holding company earlier this year, and a month ago the website sent out a warning to followers that its editorial independence was at risk. “Index is a mighty fortress that they want to blow up,” said Dull, in a farewell speech to the newsroom after his firing on Wednesday.

Having taken the difficult decision to leave their jobs in a global economic downturn and in Hungary’s bleak environment for independent media, the former Index journalists are already thinking about how they could reconstitute the project.

“We are starting to think about what can happen next. We don’t have a complete plan but we would like to stay together. We know it’s going to be really hard in this media environment in Hungary,” Munk said.

The situation at Index comes in the same week that Orbán was able to water down plans by a number of EU countries to link the future disbursal of EU funds to rule of law conditions, and drew criticism from some European politicians.

“I expressed big concerns about the situation in media in general in Hungary, and also specifically the situation in Index,” Věra Jourová, the vice president of the European Commission, said on Thursday.

A protest march in support of media freedom was planned for Friday evening in Budapest.