Former council employees Charles Owenson, 62, and James Costello, 44, received tens of thousands of pounds worth of bribes from an Edinburgh-based firm’s staff members Kevin Balmer, 52, and Brendan Cantwell, 44.

In return for the cash, the two local authority workers helped influence the awarding of construction contracts to the company for public buildings such as schools and libraries.

The first charge details how between January 6, 2006 and November 10, 2010, Balmer and Cantwell corruptly gave £42,521 cash to Owenson and Costello at various locations in the Scottish capital.

The two employees of Edinburgh-based firm Action Building Contracts (ABC) Limited also gave Owenson and Costello £30,249.21 in hospitality as an inducement to secure contracts for the repair and maintenance of Edinburgh City Council buildings.

The second charge states that Owenson, while working as an officer at the local authority’s Property Care Services Ltd, received £28,387 at various locations in Edinburgh between 2006 and 2010 as a reward for the council awarding contracts to ABC Ltd.

The third charge states Costello acted corruptly, as an officer in the same department, and received £14,134 for the council awarding contracts to ABC Ltd.

Between April 18, 2007 and May 2010, in Edinburgh, Balmer fraudulently caused Edinburgh City Council to pay ABC Ltd £67,923 for work the company carried out on behalf of the local authority.

Balmer pocketed £22,641 from the fraudulent scheme.

Between May 19 2007 and December 29 2011, at various locations in Scotland, Owenson breached Proceeds of Crime legislation by laundering £28,387 by purchasing motor cars.

Costello carried out the same scam between June 2007 and April 2012 at various locations in Scotland.

The long-running investigation concluded with a guilty plea from the four men at Edinburgh Sheriff Court yesterday.

Further charges of fraud and money laundering were also libelled against some of the men.

Sheriff Michael O’Grady adjourned the case until Friday when the court will hear the circumstances surrounding the men’s behaviour.

Detective Inspector Arron Clinkscales from Police Scotland said: “This enquiry has attracted significant media coverage due to the misuse of public funds.

“Where reports of fraud or corruption in public office are made, Police Scotland will investigate such allegations thoroughly and robustly.

“The outcome at court today endorses the hard work of Police Scotland and the partner agencies involved in a long and complex enquiry.”