A senior Dumfries and Galloway Council official has moved to reassure elected members over a police investigation into alleged corruption at council headquarters.

Acting in response to "media attention", Alex Haswell the council's monitoring officer insisted that a secret 2009 council report into a "conspiracy to corrupt the planning process" now being reviewed by police for evidence of criminality found "no evidence to substantiate any of the complaints."

In a confidential memo for the "assistance of members" issued last week and leaked to this newspaper, Haswell gave the first official acknowledgement of the existence of the so-called McCourt Report, commissioned by the then D&GC chief executive from ex-Highland Council leader Arthur McCourt. Haswell, a qualified lawyer, further states that the matter is now "sub-judice".

Until the Sunday Herald revealed police involvement this month, the outcome - and even the existence - of the corruption probe were never shared with councillors, although allegations of attempts to mislead elected members were central to the complaint and to the investigation.

Completed in April 2009, the report's findings were not divulged to Peter Hewkin, the businessman who made the compalint.

A spokesman last night declined to explain the apparent secrecy surrounding the graft probe, in light of the council's commitment to the "principle [of] taking informed and transparent decisions which are subject to effective scrutiny". He also refused to answer questions on council policy towards public complaints.

The substance of the McCourt Report concerns the attempt by Hewkin and his company ScotiaGlobal, to develop Scotland's first large-scale datacentre in Dumfriesshire. A decision to approve the £40m, 250-job scheme was overturned in a shock council decision at what was expected to be a routine stage of the planning process in August 2013.

The decision, later condemned as "unreasonable" by the official reporter in January 2014, was explicitly linked by Councillor Archie Dryburgh, a member of the planning committee, to the need to support a rival datacentre, alleged official preference for which was also the focus of the McCourt report.

According to Haswell's letter, McCourt probed charges that D&GC "conspired to corrupt the planning process by deliberately misleading elected members by providing them with untruthful information regarding the proposed datafarm development."

He also looked at allegations "that commercially sensitive information, provided by [Hewkin] was passed by planning staff to outside competing commercial interests... and the complainant had received hostile treatment [from council officials]."

In his original complaint to the council Hewkin alleged that senior officials in D&GC's planning service conspired to block his scheme, which was supported at local level by Scottish Enterprise and by senior executives at Microsoft, with supported from then infrastructure minister Nicola Sturgeon.

Council officials were accused of favouring an alleged copycat scheme by John Hume chairman of the then ailing property speculator R&D Holdings. The R&D scheme, under the name Lockerbie Data Centres was to be built over a potentially hazardous ethylene pipeline, and was dismissed by the industry as unsuitable for the storage of sensitive corporate or government data.

R&D's collapse in April 2011 while working on a £77m social housing scheme for Dumfries and Galloway Housing Partnership led to a local economic crisis. R&D and DGHP are currently the subject of demands for an official investigation on the grounds that the critical state of its finances was known at the time of the contract.