A report into governance at the Scottish Police Authority (SPA) highlighted a "damning culture of failure", it has been claimed.

HM Inspectorate of Constabulary in Scotland (HMICS) found the chairwoman and a number of board members at SPA are acting "well outwith their core non-executive roles", contrary to their agreed job descriptions and guidelines.

The report also noted there is "no clear vision, strategy or plan in place" for the SPA, which has resulted in a lack of wider understanding of the steps required to achieve its aims.

HMICS went on to state "limited progress" had been made in tackling structural issues and a "conflict of interest" is caused by the SPA being both a service provider to and scrutiny body of Police Scotland.

Scottish Liberal Democrats justice spokesman Liam McArthur, said the report highlighted a need for a new corporate structure at the SPA, as well as a review of the roles of the chair and board members.

"Scottish Liberal Democrats have warned for years that the structure of the national force embedded too much power and authority in a small number of hands," he said.

"This report clearly demonstrates that the structures managing the scrutiny of one of our most pivotal public services are ambiguous at best.

"Robust accountability of the police cannot be dependent on the whim of those who have a seat at the table."

He added: "It is this centralisation of power which has contributed to the damning culture of failure outlined in this report.

"This is not good enough for officers, staff or the public they serve. This report is clear that we need a new corporate structure and a review of the roles of the chair and board members.

"The Scottish Government and SPA must now lay out a timetable for this to take place."

SPA chairwoman Susan Deacon said: "The SPA board is actively taking forward a range of work to progress improvements in the leadership and governance of policing, much of which is actively addressing issues identified in the HMICS report.

"We are committed to continuing to work closely with a range of partners including the Scottish Government to accelerate the pace of change and improvement and to ensure that the authority is able to carry out its functions effectively as envisaged in the legislation."

A Scottish Government spokesman said: "Ministers are grateful to the Chief Inspector for this report which recognises the positive impact of the Scottish Police Authority (SPA) members in improving the effectiveness of the SPA.

"The majority of the recommendations are for the SPA to take forward and we will consider the Scottish Government's role in delivery, including providing ongoing support to the Authority.

"We have agreed with the SPA that an early action will be to jointly review the SPA's Governance and Accountability Framework, to ensure that it clearly sets out the role and expectations of the SPA Board in the context of its founding legislation, particularly in relation to its scrutiny of the national police service.

"We will clarify the practical implications of this for Board members, ensuring external assurance as appropriate."