SINGAPORE - The number of complaints received by the Corrupt Practices Investigation Bureau (CPIB) last year and the number of cases it subsequently registered for investigation have both fallen to a 30-year low.

Latest statistics released by the bureau on Thursday show that there were 136 cases registered for investigation by the CPIB last year, a drop of 11 per cent from the 152 cases registered in 2013.

Out of the 136 cases, 15 per cent involved public officers.

In all, there were 736 complaints received by the bureau last year, a 7 per cent decrease from the 792 complaints in 2013.

Some were not corruption related, but pertained to other offences such as cheating and misappropriation of public or company funds.

The bureau refers all non-corruption related complaints to the relevant authorities.

Said CPIB: "Corruption is under control and the international measures such as Transparency International and Political and Economic Risk Consultancy attest to Singapore remaining as one of the world's least corrupt countries."

"Although Singapore is one of the least corrupt countries in the world, it is important that laws must be rigorously enforced and corrupt behaviour continues to be socially unacceptable," it added.

The predominant mode through which complaints were received by the CPIB was through mail or fax, with four in 10 complaints received this way.

Close to half of the complaints which resulted in investigations, however, came through a phone call or an in-person meeting with the bureau.

A complaint lodged in person was the most effective - it was three times more likely to result in investigation, compared to an email or fax complaint.

In terms of prosecutions, 168 people were brought before the courts as a result of CPIB investigations last year. Those from the private sector comprised 88 per cent of prosecutions.

The CPIB highligted three sectors of concern from the private employees it prosecuted last year - construction; sales of household goods in departmental stores; and warehouse and logistics services.

In its release, the bureau said it continues to stay vigilant in its work to safeguard Singapore's integrity and national interests.

"The CPIB upholds the highest level of incorruptibility and remains relentless in combatting corruption through swift and sure, firm but fair action."

The bureau strongly encourages those with information about graft to contact it by walking-in to its office at 2 Lengkok Bahru, Singapore 159047; calling its 24-hour hotline at 1800-376-0000; or lodging an online complaint at www.cpib.gov.sg.