Suspended Perth Lord Mayor Lisa Scaffidi has admitted at an inquiry that she broke the law when she interfered in the council heritage listing process for a building in which she had a financial interest.

Ms Scaffidi and her husband had three-quarters ownership of the Grand Central Hotel and she excused herself from making a decision on whether it should be on the council's heritage register in March 2015.

Suspended Perth Lord Mayor Lisa Scaffidi has fronted a series of public hearings as part of the inquiry into the City of Perth. Credit:Richard Wainwright/AAP

Ms Scaffidi accepted the suggestion of counsel assisting the commissioner Philip Urquhart that she should have said she had a financial interest and could not discuss it.

"It's what you should have done by law, isn't it?" he asked.