Greyhound Racing NSW officials refused to hand over information to the RSPCA that could have helped identify a number of people suspected of involvement in live baiting due to privacy concerns, an inquiry has heard.

The Special Commission into Greyhound Racing has been told a diary which "contained very valued information" was seized during a raid in February 2015 on an unidentified trainer who was suspected of using live animals to train greyhounds on his western Sydney property.

The chief inspector of the RSPCA, David O'Shannessy, told the commission on Thursday that the society had asked Greyhound Racing NSW to identify the people in the diary, which had a list of Christian names and telephone numbers.

But Mr O'Shannessy said the racing organisation would not assist unless they received a formal notice to produce information.