That bankrolls criminal empires at considerable cost to the taxpayer in tax avoidance and benefit fraud. The is also a growing bill for patching up the human misery resulting from the trade in illegal drugs and prostitution.

This is alarming enough but, when the businesses used by criminal gangs as a means of laundering cash, typically private hire taxi firms and security companies, become so thoroughly embedded in society that they attempt to secure legitimacy by bidding for public service contracts, we reach a dangerous new tipping point.

Officials responsible for procurement in the public sector are required to award contracts on the basis of best value. While it is clearly not in the public interest to award such contracts to suspected criminals, the rules are tightly framed in terms of fact rather than suspicion. An illustration of this difficulty is the £2m contract NHS Greater Glasgow was on the brink of awarding to a taxi company until alerted by Strathclyde Police that it had been linked to organised crime. The board postponed the decision and has still to award the contract.

One welcome effect of this case, however, is that it has brought a new awareness to public bodies that unwittingly they could be financing organised crime. Procurement officials are now working with the Scottish Crime and Drug Enforcement Agency to examine how they can guard against awarding contracts to criminals within the existing rules and whether new powers are required.

It is essential that everything possible is done to prevent criminals receiving any of the £8bn of public sector contracts awarded in Scotland every year. Despite the complexities in tightening up the rules, which may require new legislation, there is a need for urgency in working within the current system to prevent crime lords profiting from contracts for major new projects such as the 2014 Commonwealth Games and the new Southern General Hospital in Glasgow.

In the meantime, existing filters such as the Security Industry Authority vetting scheme should be used by all public bodies to ensure that security contracts are awarded only to approved companies.