The latest survey from the Scottish Building Federation warns that late payments have reached ” epidemic proportions”with the average value of invoices totally written off reaching £6,000.

The figures come as it was reported that Carillion is nearly doubling its maximum payment terms to 120 days.

The move has caused outrage among subcontractors calling for a boycott of the firm.

The federation’s latest Scottish Construction Monitor found that four out of every five construction companies had suffered problems with late payments over the past year.

It warned that cash-flow for many firms was being “critically undermined”, raising the threat of business failure.

SBF said the issue was contributing to an overall lack of industry confidence.

The average builder said they were owed almost £90,000 in payments not made within stipulated periods and had been forced to write off unpaid invoices worth almost £6,000.

Federation executive director Michael Levack said: “Late payment of invoices has long been the bane of many construction firms.

“But, in the current economic climate, it risks becoming the difference between continued trading and business failure.

“For Scotland’s construction industry, this survey demonstrates that late payments have become an issue of epidemic proportions, affecting an overwhelming majority of businesses, irrespective of their size.

“What is more, a majority of construction firms have been forced to write off outstanding payments worth thousands because of persistent non-payment.

“It is a tragedy that otherwise excellent businesses are forced into bankruptcy because of a lack of the cash-flow they need to pay bills and salaries when customers fail to pay their bills on time – or at all.”