The BBC has inadvertently revealed the names of 120 female employees who have pursued gender pay complaints against the corporation in a potentially major data breach.

The list, seen by the Guardian, includes many household names and was included as part of the paperwork supporting Samira Ahmed’s continuing employment tribunal case against the BBC. It names the large numbers of BBC women who put their name to a letter issued by the National Union of Journalists in 2017 seeking a collective approach to addressing unequal pay in the organisation.

The vast majority of the names have not previously been publicly linked to pay disputes with the BBC. The document was made available in unredacted form to members of the public and journalists during Ahmed’s hearing as part of the bundles of supporting evidence.

A BBC spokesman said it was not responsible for the breach. “This list was part of the evidence that the NUJ put before the tribunal, not the BBC,” he said.

On Thursday the BBC was engaged in a frantic attempt to reassure staff on the list, emailing them to let them know that their complaint – and in some cases their pay grade – had been made public: “Although this was not the BBC’s evidence we have made clear to newspapers that we believe the names contained in the letter were not directly relevant to the case – however, they may choose to publish this information anyway and we thought you should know.”

The publication of the unredacted list came after the BBC successfully managed to convince the tribunal judges to conceal the name of a senior manager from public documents, who Ahmed alleges told her: “The BBC doesn’t do equal pay.”

Ahmed is claiming almost £700,000 in back pay for an alleged breach of equal pay legislation by the BBC in a case supported by the National Union of Journalists, which compares the fee she received for presenting the viewer feedback programme Newswatch with the amount Jeremy Vine received for presenting the similar Points of View. The BBC insists it did not break the law requiring equal pay for equivalent work, insisting they are different programmes for different audiences.

It is the first major equal pay case involving the BBC since the corporation’s policies on gender pay came under scrutiny in summer 2017 when it revealed there was just one woman on its list of the 10 highest-paid employees. However, there is speculation that another dozen could soon reach the employment tribunal stage.

Thompsons solicitors, which is representing Ahmed, has now written to news outlets asking them to hold back from publishing the names of the 120 women: “Whilst the names of the individuals may be in the public domain due to the BBC revealing them within the court bundle it would be a breach of their privacy to make approaches to them when they are not parties to the action and have not given their consent for their names to be released in this way.”

They also put pressure on the broadcaster to support the members of staff who may be affected: “We expect the BBC as the employer of the individuals named to take action to support any employees whose privacy is breached without their consent.”

An NUJ spokesperson said: “Whilst the collective grievance was referenced in the NUJ’s evidence to the tribunal, the names of BBC employees were not and should have been redacted.”