Enforcement officers, nearly all of whom were men, made up half of public officers investigated for graft and similar misconduct over the past five years.
Money was also the most common type of bribe, with cases involving sex accounting for just 11 per cent.
This is what a new study, prompted by the recent spate of high-profile cases involving public officers, established.
Commissioned by the Prime Minister's Office, it was meant to see if there were widespread issues in the public service system. The study was initially "classified" but the PMO made it public yesterday due to "public interest".
It showed that of the 996 cases handled by the Corrupt Practices Investigation Bureau (CPIB), 197 or about one in five cases involved public officers. This works out to an average of 39 cases each year between 2008 and last year.
A third of these cases saw no need for further action after the officer was cleared, investigations proved inconclusive or the Attorney-General decided there was a lack of evidence. The rest of the cases led to criminal prosecution or disciplinary proceedings.
Male officers were the bulk of offenders, forming 92 per cent of those prosecuted or disciplined.
Half of these offenders, or 51 per cent, were also front-line officers whose job was to enforce laws. They included police and anti-narcotics officers and officials from the Housing Board, National Environment Agency and Manpower Ministry, among others.
The other half, or 49 per cent, consisted of those in technical and support roles, as well as those working in administration.
About 30 per cent of those prosecuted or disciplined were A-level or diploma holders; those with degrees accounted for 23 per cent. Close to half had O-level certification as their highest qualification.
The most common accusation against those investigated under the Prevention of Corruption Act was showing unwarranted leniency when doing their job (53 per cent). Twenty-one per cent gave unauthorised services and information, and 15 per cent granted favour in the form of employment and other opportunities.
In return, 6 per cent received sexual favours and 5 per cent got a combination of sex and money.
In 65 per cent of the cases, money was the sole form of illegal gratification. The amounts were usually less than $1,000, which was so for 40 per cent of cases. Cases involving bribes of over $100,000 made up 6 per cent.
Commenting on the results, head of the civil service Peter Ong said in an e-mail sent to the 136,000-strong public service that he was reassured by the findings as they show that "our system as a whole remains sound".
Indeed, Singapore was in fifth place in last year's Corruption Perceptions Index compiled by Transparency International, which measures perceived levels of public sector corruption.
"We have a strong culture which rejects fraud and corruption," said the PMO yesterday, while highlighting how half the cases which led to prosecution and disciplinary action came from complaints within the civil service. About a third came from members of the public, and the rest from anonymous tipoffs.
These show that existing channels for reporting suspected wrongdoing "have proven useful in many cases", added the PMO.