Alistair Carmichael demanded answers from both administrations after it emerged more than £500 million of Scottish Government guarantees and hundreds of jobs could be at risk.
The failure of Greensill, a financial services company, has left many fearing that thousands of jobs at Liberty Steel’s assets in the UK could be at risk, including those who work at the Lochaber aluminium smelting plant.
It comes as calls intensified for an inquiry into former prime minister David Cameron's involvement after allegations surfaced that Lex Greensill was given privileged access to Whitehall departments.
The Sunday Times claimed the Australian financier was given access to the departments while Mr Cameron was in No.10 so he could promote a financial product he specialised in.
Now Mr Carmichael – the Orkney and Shetland MP – has claimed the fiasco has left nothing, but “clowns”.
He said: “Whether is it David Cameron’s dodgy behind-the-scenes role or Fergus Ewing’s blithe defence of a growing crisis last week, the common denominator is complacency.
"All involved appear to have assumed that no-one would look too closely at the business case and that the circus could carry on forever.
"The circus has stopped – all we have left are the clowns.
“No amount of spinning will make the Greensill-Liberty Steel fiasco look like anything other than a long-running, complete failure of judgement from both the UK and Scottish governments.
"The Conservatives and the SNP have a lot of questions to answer as to how they managed to give such a free hand to these companies on the promise of jobs and investment that have never materialised.”
Last week Mr Ewing told MSPs steel magnate Sanjeev Gupta had reassured him his Scottish companies were financially sound despite the collapse of his financiers.
Mr Gupta’s company, GFG Alliance, also operates the Dalzell and Clydebridge steel works, the hydro-electric power station at Fort William, Jahama Highland Estates and Shand Cycles. It is believed the parent firm owes Greensill more than £3 billion.
Scottish Government ministers have insisted that commercial confidentiality prevents a full explanation of the risk to taxpayers and the lack of progress on jobs.
Speaking in Parliament last week, Mr Carmichael argued that when taxpayer money was concerned, commercial confidentiality should not prevent accountability.
He said: "The Secretary of State will be aware that the Scottish Government is out for guarantees north of £500m as a consequence of Greensill’s difficulties. Is that not something for which there really ought to be full explanations?
“They say a picture is worth a thousand words – and apparently an SNP photo shoot and grandstanding over jobs that never materialise is worth risking £500m of taxpayer money.
“The pattern over the past few years is clear. The SNP splash the cash, turn up to get their picture taken and then the whole edifice slowly topples over. Is it too much to expect someone – anyone – to take responsibility for actually delivering on jobs?”
Labour's shadow business secretary Ed Miliband has previously labelled the GFG Alliance situation "urgent and worrying" and hinted at nationalisation.