Prime Minister Lee Hsien Loong's siblings Lee Wei Ling (LWL) and Lee Hsien Yang (LHY) had threatened to embarrass him during the 2015 General Election by spilling details about the tussle over their late father's house.
"Matters reached the point where LWL and LHY threatened to escalate their attacks against me, coinciding with the September 2015 General Election," PM Lee said. "I was not prepared to be intimidated."
This was in a statutory declaration he made to a ministerial committee set up to consider options on the house at 38, Oxley Road.
In the declaration, he revealed his deep misgivings about his father's final will and said these circumstances had called into question Mr Lee Kuan Yew's thinking and wishes in relation to his house. Mr Lee had died on March 23, 2015.
In August that year, a general election was called, with polling day on Sept 11. During the election period, a dispute between PM Lee and his siblings had not been resolved, and he was threatened over it.
The future of the late Mr Lee's house had become a point of contention for the three siblings.
Dr Lee and her brother Lee Hsien Yang had expressed unhappiness that their father's house was bequeathed to PM Lee.
Mr Lee Hsien Yang also wanted it demolished right after Mr Lee's death, a move PM Lee opposed as he felt it was too soon and people's emotions were still too raw.
PM Lee said he was concerned this might force the Government to react by deciding to gazette the house, which would not be in the best interests of the late Mr Lee's legacy or Singapore.
Subsequently, PM Lee offered to transfer the house to Dr Lee for a nominal sum of $1, subject to some conditions, but this was not accepted by his siblings.
The family dispute was not resolved by the time the election was called. The People's Action Party won it with 69.86 per cent of the popular vote, its best election result since 2001.
In his declaration, PM Lee said he was not prepared to be intimidated as his siblings' accusations were baseless. He also said the accusations were made on the premise that nothing unusual surrounded the circumstances of how their father's final will was made.