Richard Leonard has called for Nicola Sturgeon to give up the SNP’s right to chair a special committee established to look at the handling of complaints made against Alex Salmond.
The Scottish Labour leader said in a letter to the First Minister that an MSP from an opposition party must instead be appointed to oversee the committee’s work.
Under parliamentary precedent the SNP is due to chair the next committee established in Holyrood.
At First Minister’s Questions on Thursday, Ms Sturgeon refused to answer calls from Mr Leonard that the SNP give up the convenor’s position.
Mr Leonard has now written to Ms Sturgeon calling for the SNP to step aside and let an MSP from an opposition party chair the inquiry.
In the letter, he said it was in “the interests of transparency, integrity and objectivity” that the convener did not belong to the same political party as the Scottish Government.
It was confirmed this week that a special committee of MSPs will be set up to look into the collapse of the government investigation after allegations by two women about Mr Salmond. He denies the claims.
A separate police investigation is ongoing.