“Systems are composed of human beings,” Lee said. “In any system, however comprehensive the safeguards, sometimes something will still go wrong.”

In response to Lee’s speech, the WP’s chief Pritam Singh assailed the government for what he claimed was a pattern of being slow to release information on events that put the ruling party in a bad light.

“In this term of government, the government has either been slow to clear the air or been less than upfront and forthright with Singaporeans when it had to deal with potentially embarrassing issues,” he said.

Singh, the leader of the opposition, raised the example of the government’s response to the MPs’ affair and Iswaran’s July 11 arrest, as well as two other recent episodes.

Both probes found the ministers committed no wrongdoing, but the formal anti-corruption probe was only revealed when the findings of both investigations were made public on June 28.

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Singapore’s political scandal deepens as 2 MPs resign amid separate high-profile corruption probe

Singapore’s political scandal deepens as 2 MPs resign amid separate high-profile corruption probe

“Unlike as represented by the PM, these are not events that I quote ‘are clustered together, all coming in one go’,” Singh said in his remarks. The opposition chief accused the PAP of “engaging in half-truths on matters of significant public interest”.

This behaviour, Singh said, was the main reason behind “disquiet among Singaporeans” over the ruling party’s constant comments about trust in government and its invocation of its founding generation of leaders.

He cited these examples as justification for the need for an appointment of an ethics adviser, urging Lee to “reconsider his position in view of the PAP’s pattern of behaviour in this term of government, especially when a potentially embarrassing issue comes up”.

Singh’s hard-hitting remarks drew equally forceful responses from the PAP front bench.

Prime Minister Lee described the opposition leader’s remarks on the delay in the transmission of information as “pursuing a red herring”, saying there were questions to be asked about how the WP handled Perera’s affair with party colleague Nicole Seah.

Singh and other party leaders have faced some criticism on social media over their handling of the saga. They had questioned Perera and Seah after hearing allegations of their affair from Perera’s driver, but the matter was dropped following denials.

Later on in the debate, the prime minister – responding to Leong Mun Wai of the minor opposition Progress Singapore Party – suggested the matter was being debated in parliament in the first place precisely because of the PAP’s responsiveness to wrongdoing within its ranks.

“The reason this is here at all is because this government decided to act. ‘Ownself check ownself’,” Lee said, using a Singlish phrase first coined by Singh to deride the ruling PAP’s claim that it did not require an opposition to keep it in check.

“Otherwise, it wouldn’t even be here,” he added, referencing Leong’s remarks on Iswaran.

Singaporeans weigh morality in politics as adultery, corruption sagas ‘blow up’

Balakrishnan, who was in Singh’s cross hairs over the TraceTogether affair – he was the minister in charge of the platform – strongly denied the opposition chief’s “insinuation” that there had been undue delay or attempted obfuscation on his part.

Despite questions for more details on the probe involving Iswaran – the country’s highest-profile graft investigation in four decades – Lee and Chan Chun Sing, the minister in charge of the public service, offered few new details as the investigation was ongoing.

There has been some speculation that the probe may have to do with the republic’s hosting of the Formula One night race.

Additional reporting by Bloomberg