Mr Lee Hsien Yang last night made plain that the target of his attacks is his brother Prime Minister Lee Hsien Loong, and not the Government.
In his latest Facebook post, he argued that he was not hitting out at the Singapore Government, but his brother, for failing to live up to the high standards of integrity that his father Mr Lee Kuan Yew had set for those in public service.
"To show evidence that he has failed to meet these standards is not to attack the Singapore system, but to preserve it," said Mr Lee Hsien Yang. The legacy of their father, founding prime minister Lee Kuan Yew, was more than "bricks and mortar", for he "made sure all government officials acted with justice and integrity", he added.
"He accepted nothing less than incorruptibility, especially for the very top. Singapore can yet live up to his legacy," he said.
He repeated his previous statement that he and his sister Dr Lee Wei Ling "are disturbed by the character, conduct, motives and leadership of our brother".
"Since Lee Kuan Yew's passing, we have felt threatened by LHL's misuse of his position and influence over the Singapore government and its agencies to drive his personal agenda," he said.
He and Dr Lee want to demolish the 38, Oxley Road house, saying it is in accordance with their father's wishes. They have alleged that PM Lee abused his power to try and preserve the house for political gain.
PM Lee has denied their claims.
Emeritus Senior Minister Goh Chok Tong told Parliament on Tuesday that the siblings were not "whistle-blowing in a noble effort to save Singapore", rather they were waging a personal vendetta against their brother PM Lee.
Mr Goh said: "From what Lee Hsien Yang and his wife are freely telling many others, it is clear that their goal is to bring Lee Hsien Loong down as PM, regardless of the huge collateral damage suffered by the Government and Singaporeans."
Yesterday, Mr Lee Hsien Yang did not deny this point in his post. He said the "private family dispute" would not have spilt into the open had PM Lee not used government agencies and a ministerial committee to push his agenda.
"Sadly, it is Lee Hsien Loong who has dragged the Government into a personal dispute," he said.
He was referring to a ministerial committee considering options for the house. However, Deputy Prime Minister Teo Chee Hean had told the House on Monday that well before it was formed, allegations of abuse of power were already being made in smaller circles.
Mr Lee Hsien Yang added that the PM and his wife should not be above the law, adding that PM Lee should abide by the same standards expected of junior civil servants.
Last night, Law and Home Affairs Minister K. Shanmugam shared a clip of Mr Goh's remarks in Parliament on Facebook, adding: "ESM Goh Chok Tong says what Lee Hsien Yang's real motive is - jealousy, bring down PM Lee Hsien Loong, using house as excuse."