Enhancing transparency was an effective way to gain public trust and confidence, said Patricia Lui Lai-kwan, acting regional officer with the anti-corruption agency.

The open days come as public trust in the ICAC is being eroded by its slow progress on several high-profile investigations against top political figures. The agency has also been bruised by accusations its former chief Timothy Tong Hin-ming misused public funds.

One of those hoping for some insight was civil servant Winter Wong Yiu-tung, 33.

"I'm afraid in these past few years the public has lost trust in government. Maybe the open day can help improve its image," he said.

Among the special exhibits were three logbooks of former police chief Peter Godber, who was jailed for corruption in 1976. The logbooks were key evidence, and the case led to the creation of the anti-graft agency.

Another visitor, hotelier Bernard Wong Ho-leung, 44, said: "My wife and I brought our two sons here to let them know how bad corruption is and to learn about the work of the ICAC."

Recent surveys have pointed to a general decline in confidence when it comes to corruption.

In August, public perception of how corruption-free the city is fell to a 15-year low in a University of Hong Kong poll.

It slipped from 77 to 75 out of 100 in last year's Transparency International Index.

And while the city's economy was still rated the freest by the Heritage Foundation this year, it was rated only the twelfth-freest from corruption.

"We do make reference to these indicators but there are so many indicators in the public domain," Lui said. "There might be slight fluctuations from year to year, but we look on the overall trend - if it is dropping somehow, we will look critically for a reason behind that."