The investigation into the Scottish Government’s botched handling of harassment claims against Alex Salmond is being “completely frustrated” by a lack of evidence from key witnesses, an MSP has said.

Convener Linda Fabiani said the Holyrood committee is facing “obstruction” as it seeks evidence about how the Government handled complaints of sexual misconduct against Mr Salmond when he was first minister.

Ms Fabiani revealed the committee was still waiting for responses from the Scottish Government, Mr Salmond and SNP chief executive Peter Murrell.

Committee member Jackie Baillie accused the Government and other witnesses of treating the inquiry as a “laughing stock”.

The committee continues to be completely frustrated with the lack of evidence and, quite frankly, obstruction it is experiencing

The probe by the committee was launched in the wake of the Court of Session’s ruling the Government had acted unlawfully in its investigation of the former first minister, who was awarded £512,000 of public money for his legal costs.

Ms Fabiani said it has been repeatedly frustrated by the refusal of witnesses to provide evidence and urged them to “engage productively” so the committee can proceed with its enquiry.

The SNP MSP said: “The committee continues to be completely frustrated with the lack of evidence and, quite frankly, obstruction it is experiencing.

“We had hoped to be in a position to hear further oral evidence but with responses still outstanding from the Scottish Government, chief executive of the SNP and the former first minister, all of this means that we simply cannot proceed at this stage.

“We have no choice but to meet in private again next week (October 6) to review the evidence we have received to date.

“I would urge all those we have approached to engage productively with the committee so it can get on with the task in hand.”

Ms Baillie, who is Scottish Labour’s deputy leader, said: “Quite frankly, the Scottish Government and others are treating this committee as a laughing stock.

“It is all too clear that the Government’s commitment to transparency was little more than a bad joke and that they are determined to prevent the committee from executing its vital task.

“The Scottish Government and, indeed, many others involved in this affair have demonstrated contempt for this committee and its aims.

“The secrecy must end and the Scottish Government and others must stop treating elected representatives as annoyances.”

Both the Scottish Government and Mr Salmond’s lawyers have argued there are legal obstructions preventing them from handing over documents.

The legal wrangling has seen Mr Salmond offer to appeal to the courts to be allowed to release papers used in his successful judicial review.

Deputy First Minister John Swinney has said the Scottish Government “intends to initiate legal proceedings to seek a ruling” about whether documents relating to the case can be released.

Ms Fabiani has also written to Mr Murrell asking for all “relevant information and records” about the use of SNP communication channels for official government business and those relating to the inquiry and the claims against Mr Salmond.

She demanded “any and all” evidence of communications about the allegations against Mr Salmond, including “emails, minutes, notes, texts, papers and WhatsApp messages from all levels of the SNP.”