An aide to an SNP MSP who received a warning for posting pro-IRA messages on social media has passed his party’s vetting to be a council candidate.

Allan Casey, who wrote “Up the Provos” and praised former IRA members on his Facebook account, is now eligible to seek selection for the SNP.

A Scottish Conservative spokesman said: “Comments of this nature have no place in political discourse, and it raises serious questions over whether this individual is fit to run for election.”

Casey is a parliamentary assistant to Glasgow Provan MSP Ivan McKee, who was elected to Holyrood for the first time in May.

The Sunday Herald revealed last year that Casey had expressed hardline views on the Troubles and his Facebook account contained messages that were supportive of the IRA.

In April 2012, he wrote: “volunteer martin Doherty rfb no1 real pride of govan, up the provos – sinn fein abu.” [sic]

Doherty was an IRA volunteer until he was shot and killed in 1994 by the Ulster Volunteer Force, a loyalist terror group.

In the same month, he highlighted the “Annual Volunteer Martin Doherty Commemoration Weekend Events”, which included a set by the Republican Flute Band (RFB) he was linked to.

Weeks before that post, he wrote of IRA volunteers Declan Martin and Henry Hogan: “Killed on active service 28 years ago today while engaging in a gun battle with undercover SAS scum.”

He also wrote: “Your deeds would shame all the devils in hell – f**k the brits, remember bloody Sunday 30th January 1972.”

He also remembered “Vol [volunteer] Pearse Jordan” – who was killed by a Royal Ulster Constabulary officer in 1992 – by writing: “A brave son of Ireland We Will Not Forget You.”

When alerted to the messages, an SNP spokesperson said: “The posts in question are from several years before Mr Casey joined the SNP or worked for any parliamentarians.

“Mr Casey acknowledges that these posts were in extremely poor taste and has deleted them. His employer has reminded him of the high standards expected of staff. Mr Casey has been warned about his behaviour and understands that any repeat would be unacceptable."

Despite the row, Casey may be part of the SNP’s team of candidates who want to take control of the council in Glasgow from Labour.

SNP officials have been interviewing hundreds of applicants who have expressed an interest in standing for the party in May.

Applicants are vetted and, if they make the grade, go on the register of approved potential council candidates. It is understood Casey has made the cut and has also been nominated by a branch.

The row comes after SNP MSP John Mason wrote that the members of the IRA who killed three Scottish soldiers could be considered as “freedom fighters”.

Asked on Twitter whether he would support a private prosecution of those suspected of murdering the three men, Mason replied: “You say Irish murderers. Others say freedom fighters. I support Scottish soldiers if they do good but not if they do bad.”

The comments led to First Minister Nicola Sturgeon apologising to the families of the dead soldiers for the “upset caused” by Mason’s comments. Mason also said sorry.

A Scottish Labour spokesperson said: "Days after Nicola Sturgeon was forced to apologise for the comments of John Mason and the IRA this is another headache for the First Minister. The SNP need to explain why they think Mr Casey is a suitable candidate for local elections."

An SNP spokesperson said: “The posts in question are from several years before Mr Casey joined the SNP. Mr Casey previously acknowledged that the posts were in extremely poor taste and deleted them.”