The Competition Commission is seeking views and comments on its latest working papers as part of its investigation into the Big Four domination of the UK audit industry.

The newly published papers Development of the statutory financial audit and Framework for the CCs assessment and revised theories of harm, further expand on the Competition Commission's Issues Statement published in December 2011.

It sets out the Commission's proposed framework for the assessment of competition in the supply of audit services to FTSE350 companies and outlines some key areas for exploration, such as the economic role of audit services, competition and the high barriers to entry for non Big Four auditors.

The body explores what may be contributing to the current characteristics of the market and the potential 'adverse outcomes that may be present as a consequence of weak competition'.

As part of that probe, the Commission published the findings of an in-depth survey of over 600 CFOs, FDs and chairs of audit committees (AAC), focusing on the statutory audit of FTSE 350 companies.

It found that FTSE 350 companies had been with their current auditor for an average of 11.3 years; the non FTSE 350 average is 8.7 years.

Nearly four in 10 (37%) companies used the same Big Four auditor for over 11 years, with 14% sticking with the same firm for over 20 years.

Signs of complacency over putting the business out to tender were revealed with one in five (21%) companies, using the same audit firm for over a decade, having never gone out to tender.

Both working papers can be accessed from the Compeition Commission. Comments should be received by September 7.