Several senior staff at a German consultancy on Wednesday distanced themselves from an audit conducted by their firm of a Volkswagen joint-venture in China's Xinjiang province that found no evidence of forced labour at the plant.

Under heavy investor pressure, Volkswagen commissioned Loening GmbH to audit its jointly owned site in Xinjiang, a region of China where rights groups have documented abuses including mass forced labour in detention camps. Beijing denies any such abuses.

In a statement on Dec. 5 detailing the results of the audit, Loening GmbH's founder and chief executive Markus Loening said his firm had found no signs of forced labour at the plant, a joint venture with SAIC Motor, while noting the challenges of data collection in China.

Later that week, Loening GmbH posted a statement on its LinkedIn page that said that apart from Markus Loening and senior strategy adviser Christian Ewert, as well as two Chinese lawyers, "no other team member participated in, supported or backed this project"...

After Reuters reported on the statement on Loening's LinkedIn page, Markus Loening told Reuters that the team had "a spectrum of views" and projects were always carried out by small expert teams - in this case himself and Ewert, supported by two Chinese lawyers.

"My assessment of it as project director and chief executive is public and unchanged," Loening added.

Some Volkswagen investors reacted cautiously to the results of the audit last week, welcoming that it had been carried out but adding that it could not be a one-off and should be the first of a series of steps to improve transparency in the carmaker's supply chain in China.

Volkswagen declined to comment.