Unite assistant general secretary Gail Cartmail made the demand at the TUC Congress in Manchester on Monday.

She said: “Eight months after Carillion’s collapse the Insolvency Service is only just beginning to investigate if laws were broken. This is simply too little too late.

“There must be an immediate criminal investigation into Carillion. And we the trade union movement must lead that call. If no laws were broken, then we need, better, stronger laws.”

When Carillion collapsed it had £7bn of liabilities, including a £2.6bn deficit in its pension funds with just £29m left in the bank.

Unite said: “The company had 19,000 employees over 3,000 of whom were made redundant.

“There were a further 35,000 people employed in Carillion’s supply chain and via subcontractors.

“Many of these companies went to the wall and hundreds if not thousands of workers have lost their jobs.”

Cartmail added: “The government and other organisations are treating Carillion’s collapse as business as normal.

“There is nothing normal about the biggest corporate collapse in the UK’s history.

“While thousands of workers have been thrown on the scrapheap, those responsible for driving the company into the ditch, have dusted themselves off and started again as if nothing had happened.

“If nothing criminal occurred then we should be told how on earth it can be legal to have embarked on the policies pursued by Carillion’s management team which drove it to the wall with little prior warning.”