A joint communiqué, issued by ILAC (International Laboratory Accreditation Cooperation), IAF (International Accreditation Forum) & ISO (International Organisation for Standardisation), has been published to reinforce the fact that accredited inspection bodies operate a recognised quality management system.
Until now, accredited inspection bodies were often requested by their customers to undertake the additional step of gaining certification to ISO 9001:2008 to demonstrate that they are in full control of their processes. The communiqué clarifies that inspection bodies accredited to ISO/IEC 17020:2012 are recognised as meeting the pertinent requirements of ISO 9001:2008.
ISO 9001:2008 is the internationally recognised standard for quality management systems.  Its requirements are generic and applicable to all organisations, regardless of type, size and product provided.  ISO/IEC 17020:2012 is a specific standard which sets out the requirements for organisations performing inspection activities.  Whilst it is chiefly considered a measure of the technical competence of an inspection organisation, ISO/IEC 17020:2012 also includes a series of management system requirements (Section 8).
The communiqué is therefore designed to reduce the need for redundant audits of accredited inspection bodies, allowing them to focus on delivering reliable and high quality services to their customers. 
Copies of the communiqué can be downloaded from both the ILAC and IAF websites:
https://www.ilac.org/partnerships.html
http://www.iaf.nu/articles/Communiques/26