A former senior policeman has been appointed as Scotland's third judicial complaints reviewer amid controversy over the legal watchdog's role.

Justice Secretary Michael Matheson announced that from September, retired Tayside Police deputy chief constable Ian Gordon will take up the position, set up to review the handling of complaints into members of the judiciary.

Mr Gordon is currently an acting commissioner with the Northern Ireland Public Service Ombudsman Office and has conducted criminal, conduct and complaints investigations in the UK.

His appointment follows comments from the outgoing reviewer Gillian Thompson about the constraints of the role and a lack of support.

She conceded in a recent report that these limitations meant the role offered a "poor service, relatively speaking" and called on Scottish ministers to "review the relevance of the role as it exists".

The previous incumbent Moi Ali resigned in 2014 claiming the role had no power.

Scottish Liberal Democrat justice spokesman Liam McArthur has written to Mr Matheson backing Ms Thompson's call for a review.

In the letter, he said: "I of course wish Ian Gordon well in his new role. However, there is no avoiding the fact that the previous two holders of the post have both condemned the support they received and claimed that this has had serious implications for the quality of the service they have been able to provide.

"The only two holders of the post have both provided blistering accounts of their experiences. In appointing the third JCR the Scottish Government cannot ignore the criticisms of his predecessors and the serious questions that surround the credibility of this office. It is clear that the current system is not working.

"I therefore urge you to act on Ms Thompson's calls for a review of the 'relevance' of the post. Almost a decade on from the Act that created it, I believe there is a strong case for this review examining whether the legislation is fit for purpose and whether the JCR has the resources they need to do the job with diligence and timeliness.

"It would be irresponsible for the Scottish Government to once again ignore these concerns and risk leaving the new holder of the post similarly hamstrung."

A Scottish Government spokesman said: "The Scottish Government has provided support for the previous JCR whenever requested, particularly in relation to website and IT issues, and we will review these arrangements with Mr Gordon when he takes up post in September."

He added that the government is always receptive to requests from the reviewer to work additional days when their workload demands.