Problems with pre-qualification questionnaires (PQQ), prompt payment and a bias towards larger suppliers on framework agreements were among the main trends identified in both the December 2012 and February 2014 Cabinet Office reports on the service.

While the government reported a decline in the percentage of procurement process issues reported in the second 18 months of the service, from 75% of all issues raised to 50%, it saw a rise in the proportion of these related to PQQs, up from a third to half of all process complaints.

The most common of these related to the assessment of bidders' financial strength, with some contracting authorities demanding three years' audited accounts and using levels of turnover as single assessment criterion. Another common complaint was PQQs that required considerable text and data input, even for low-value contracts.

Prompt payment of contractors and sub-contractors was a trend in both reports, as well as payments not being made in accordance with the terms of the contract or (in the second report) not being made at all.

In the case of frameworks, SMEs continued to report a bias towards larger suppliers in the February 2014 report, as demonstrated by "overly short timescales being set for mini competitions when calling off from framework agreements" and "the acceptance of 'pro bono' [or] uneconomic bids".

BPIF president Kathy Woodward agreed that these were all common problems reported by printers tendering for public sector contracts and added that she had come across a number of equally damning new trends.

"There is now a situation with government contracts where the holder is required to open house to people who are tendering, giving them access to confidential information of the business," she said.

"Equally some authorities are now contracting third parties to carry out 'ethical audits' of suppliers that sometimes require higher standards than those required by legislation. Yet those same terms and conditions are not then imposed on, for example, overseas sub-contractors.

"I feel very strongly that we should be giving priority to UK-based businesses, which is something EU legislation allows you to do in terms of developing UK industry, but things like these ethical audits means SMEs are not going to be competing on a level playing field."

BAPC chairman Sidney Bobb added: "There's probably been a slight improvement on prompt payment from the public sector because of all the publicity around it but nothing else has changed.

"I also know of a number of printers who have been supplying public sector organisations for years when suddenly a compliance officer has noticed they aren't on the approved supplier roster and then they've had to jump through so many hoops just to continue supplying a customer that has been satisfied for years and years.

"It's time-consuming and frustrating."

The Mystery Shopper Service, which was launched in 2011, encourages suppliers to report poor procurement practice in the public sector; it has received more than 600 reported cases since its inception.