Trade unions piled pressure on Scottish Finance Secretary John Swinney to act yesterday as he again ducked calls for a blacklisting inquiry.

Officials from the construction industry's Unite and Ucatt unions offered a cool response after the SNP minister punted the prospect of a public inquiry off into the horizon.

Union warnings over the practice were first vindicated in 2009 when a raid on blacklist firm the Consulting Association retrieved a database of 3,200 names.

No fewer than 44 firms were implicated as clients and worryingly, investigators said the database's entries included information that could only have come from police or MI5 agents.

In May Mr Swinney referred all calls for an inquiry to Westminster MPs on the Scottish affairs committee.

The committee has since demanded an inquiry from Westminster Business Secretary Vince Cable over evidence of blacklisting on London's Crossrail project just over a year ago. Chairman Ian Davidson MP said he was "neither convinced nor impressed" by the construction industry's response in the wake of the Consulting Association raid.

But when quizzed again on Thursday in light of the new findings, Mr Swinney's answer was little different.

"It would not be appropriate for the Scottish government to conduct an inquiry at this time or pre-empt any conclusions or recommendations that the committee is considering," he said.

The committee is now in its 19th month, with no date set for the final report's release.

Scottish Labour MSP Neil Findlay, who questioned the minister, told the Morning Star the SNP could not simply wait for Westminster.

"Blacklisting is a human rights issue, human rights are a devolved issue - so we could hold it here in Scotland," he said.

Unite political officer Jackson Cullinane, who also chairs Scottish Labour, said the union had welcomed the SNP's "positive" moves to allow public bodies to disqualify blacklisting companies from bidding for contracts.

But more could be done, he said - including an inquiry into blacklisting in Scotland.

The retort also comes as trade unions across Britain prepare for a national day of action next Wednesday against blacklisting.

Ucatt regional secretary for Scotland Harry Frew said that the union was as determined as ever to end the "disgusting practice."