During the illegally taped conversation the unnamed officer from the council's leisure department talks to an employee of a local firm about a possible contract.
He reveals that he has considered investing in a private firm which could have become a supplier of equipment to the council.
The officer also discusses confidential council information.
An interview took place but the officer resigned before any charges were put to him. It is understood that while he accepted the tape compromised his position he denied any wrongdoing.
A separate investigation into the identity of the phone tapper has also been launched and police are investigating.
The tapes are thought to have been made by someone with legitimate access to council offices. The officer who is heard on them is understood to believe he was framed by another employee who wanted to discredit him and who has waged a vendetta against the department.
Mr Hooker said: 'On the basis of what was on the tapes I felt an investigation was needed.
'I interviewed the employee who had been suspended but no allegations had been put to him when he resigned.'
With regard to the investigation to find the telephone tapper he said: 'Even if their intention was to uncover something, tapping telephones is illegal and a breach of their terms of employment.'
Three years ago the leisure department at Salford was involved in another anonymous tip-off when it was claimed a council employee lent another worker a canoe to use on holiday.
The canoe was never returned but photographs purportedly showing the 'missing' canoe under a caravan at a Welsh holiday spot were later sent to council leader Bill Hinds.
No employees were disciplined and the canoe was never recovered.