ARTICLE AD BOX
The SNP's Westminster leader, Ian Blackford, has announced an external review of support available to party staff who make complaints.
It follows the suspension of MP Patrick Grady after he was found to have made a sexual advance to a teenage SNP staffer.
The handling of the complaint has drawn criticism from the victim.
Mr Blackford said he regretted that the complainant did not feel fully supported.
The staffer said his life had been made a "living hell" after he lodged a complaint against the Glasgow North MP.
Mr Grady was suspended from parliament for two days after an independent panel found he had touched and stroked the neck, hair and back of a colleague during a social event in 2016.
The former SNP chief whip, who was also suspended from the party for a week, told the House of Commons he was "profoundly sorry".
In it he can be heard apparently encouraging colleagues to "give as much support as possible" to Mr Grady.
Another SNP MP, Amy Callaghan, who is also apparently heard on the tape, later apologised.
In a statement published on Tuesday, Mr Blackford said Mr Grady's inappropriate behaviour towards a member of staff was "completely unacceptable and should never have happened".
"I'm sorry it did," he added.
External review
The MP for Ross, Skye and Lochaber said staff must have full confidence the SNP Westminster group takes complaints seriously and they have a right to feel fully supported when a complaint is made.
"I regret that the complainant does not feel that this is the case," he said.
"The way that this situation has played out publicly over the last few days, including recordings from the parliamentary group, has caused distress to the complainant amongst others and I am sorry that is the case.
"We will consider all lessons that must be learned to make sure staff have full confidence they will receive the support they need.
"As such, I am initiating an external review of support available to staff, to sit alongside the independent advice service and independent complaints process.
"Raising complaints of this nature is never easy, and I am determined that staff have the support they need."
Scottish Conservative Party chairman Craig Hoy repeated his party's calls for Mr Blackford to resign.
He said: "It's astounding that it took Ian Blackford this long to realise he should apologise.
"The SNP Westminster leader has shown appalling judgement and is only now saying sorry in a desperate bid to save his own skin.
"His credibility is in tatters and he must go, so that no victim is ever let down this atrociously again."
Scottish Labour's Neil Bibby said: "This is not a real apology, it is the apology of someone who got caught."
He also called for Mr Blackford to stand down.
"From the start, the SNP have behaved in a way that is disgraceful - closing ranks and intimidating people who tried to bring this story to light," he said.
"There is no place in politics for men who turn a blind eye to abuse because it has been perpetrated by a friend.
Appeal won
Meanwhile the BBC has been told that SNP MP Patricia Gibson has been cleared of allegations she made inappropriate comments to a male staff member.
The staffer in question was the same person who made the complaint about Mr Grady.
This complaint was upheld by Parliament's Standard's Commissioner, which Ms Gibson appealed.
On 28 March the commissioner had found she had broken parliament's sexual misconduct policy, but not victimised the complainant. The findings were passed to parliament's Independent Expert Panel to decide on sanctions.
The BBC understands Ms Gibson won her appeal and has now been cleared by the independent panel.
The SNP has been approached for comment.