Parliament is not the correct forum to look into allegations made in the Oxley Road dispute, said Mr Lee Hsien Yang, adding that he has "no confidence that a fair, transparent or complete account of events will be told".
The younger brother of Prime Minister Lee Hsien Loong took to Facebook again yesterday, this time to voice "serious concerns" about the Prime Minister delivering a ministerial statement in Parliament on Monday to refute his siblings' charges.
"Only his side of the story will air, with no promise of truthfulness due to parliamentary privilege," said Mr Lee Hsien Yang. "Indeed, it could also be an opportunity to continue to mislead or insinuate under this privilege."
It is the latest twist in an ongoing feud over the fate of the late Mr Lee Kuan Yew's house at 38, Oxley Road.
The dispute erupted into the public sphere on June 14, when Mr Lee Hsien Yang and his sister, Dr Lee Wei Ling, issued a six-page statement on Facebook accusing their elder brother of abusing his powers in a bid to prevent the demolition of the house.
They also declared that they had lost faith in PM Lee as both leader of the country and brother, and made several allegations. Among them is the claim that PM Lee was misusing his influence over the Singapore Government and its agencies "to drive his personal agenda".
On Tuesday, in response to media queries on the various Facebook posts by his siblings, PM Lee said that the allegations about what he supposedly did or did not do "are mostly inaccurate".
PM Lee had added: "As I earlier said, I will be making a statement in Parliament on July 3, 2017. I will at that time deal with the allegations that need to be addressed."
PM Lee has also instructed that the People's Action Party's (PAP) party Whip be lifted, and urged all MPs, including non-PAP MPs, to examine the issues thoroughly and question him and his Cabinet colleagues vigorously, adding that he hoped this full, public airing "will dispel any doubts that have been planted and strengthen confidence in our institutions and our system of government".
Yesterday, Mr Lee Hsien Yang described the Prime Minister's move to address the allegations on July 3 as an attempt to "cover up and whitewash himself" in Parliament.
He called the parliamentary session "yet another example" of how PM Lee has misused "his position and influence to drive his personal agenda".
The session, he said, is a forum that again places PM Lee before his subordinates who, he claimed, lack sufficient background and evidence of "the numerous instances of abuse and conflicts of interest, many yet to be raised".
"Even before the session, many of them appear to have felt obliged to give him cover. Many MPs will fear career repercussions if they speak out against their superior," said Mr Lee Hsien Yang. "Historically, few PAP MPs have dared to dissent even when the party Whip was lifted."
He added that there is no opportunity or adequate time for evidence to be properly drawn together, placed before Parliament and considered. Neither will there be any opportunity for an examining body to properly probe explanations or excuses.
Mr Lee Hsien Yang said: "We believe that key issues such as his abuse of power will be simply swept under the carpet. The accused controls both process and outcome in this forum."
In the past weeks, the two younger Lee siblings have raised several instances that they claim illustrate PM Lee's misuse of power and influence.
They have, for one thing, accused him of abusing his power to obtain a deed of gift directly from the National Heritage Board (NHB) in his private capacity.
The deed concerns the donation and public exhibition of items belonging to the late Mr Lee for an NHB exhibition on Singapore's founding fathers last year.
National Development Minister Lawrence Wong, who was then Minister for Culture, Community and Youth, responded to say that PM Lee was given the deed in his official capacity.
Another bone of contention has been a ministerial committee that was set up to study options for the house. The two younger Lees have charged that the committee was shrouded in secrecy, and formed to block the demolition of the house.