Mr Lee Hsien Yang, the younger brother of Prime Minister Lee Hsien Loong, is making preparations to leave Singapore with his wife, but does not know yet when he will leave and where he will be going.

He told The Straits Times yesterday that it was the only sensible option left for him. "There are many ways people are made to feel uncomfortable," he added. "I am a person who spent his life here, who has done public service, contributed in the private sector. This is my home. I wouldn't do this unless I really felt there is a serious issue.

"And I have felt this is not where I can continue to live, the way I have been living in the last two years."

Mr Lee Hsien Yang, 59, chairman of the Civil Aviation Authority of Singapore, was elaborating on a statement that he and his sister, Dr Lee Wei Ling, had issued in the wee hours of yesterday morning.

They said they felt closely monitored and feared the use of state organs against them.

The situation made Mr Lee feel compelled to leave Singapore "for the foreseeable future", said the statement which centred on a dispute over the house of their late father, former prime minister Lee Kuan Yew.

Following the release of the statement, The Straits Times went to Mr Lee Hsien Yang's home around 10.30am.

He had already left for work. His wife, Mrs Lee Suet Fern, 59, a top corporate lawyer, was on her way to work. She said they were making preparations to leave Singapore.

But Mr Lee told The Straits Times later yesterday that he had yet to decide when to leave or where he was heading.

He also added that if PM Lee was no longer in a position of power, "I would reconsider my position".

He also said his three adult sons, Shengwu, Huanwu and Shaowu, do not live with him any more and would make their own decisions.

Eldest son Shengwu, a junior fellow at the Harvard Society of Fellows, posted the statement on his Facebook page and said: "I generally avoid commenting on Singapore politics, but this is an exception. In the last few years, my immediate family has become increasingly worried about the lack of checks on abuse of power.

"The situation is now such that my parents have made plans to relocate to another country, a painful decision that they have not made lightly."

Mr Lee Hsien Yang and Dr Lee, 62, are joint executors and trustees of the estate of their late father, and have pushed for his house at 38, Oxley Road to be demolished, in keeping with his wish as stated in his will.

In December 2015, PM Lee, 65, had also said in a joint statement with his two siblings that he hoped the Government would allow the late Mr Lee's wish to be honoured, adding that he would recuse himself from government decisions on the house.

But yesterday, his two siblings said in a statement they had lost confidence in him, and alleged that he had worked behind the scenes to preserve the house as it would allow him "and his family to inherit a tangible monument to Lee Kuan Yew's authority".

As proof of this, Mr Lee Hsien Yang cited the setting up of a ministerial committee on the house.

He said this showed PM Lee did not recuse himself from all government decisions on the house as he had pledged to do.

But Cabinet Secretary Tan Kee Yong said in a statement yesterday that the PM "has not been involved in Cabinet's discussions concerning this committee. As he had previously stated, he has recused himself from all government decisions concerning the house".

He added in a statement that the committee was set up to consider the options for the house and their implications. These included looking into aspects such as the historical and heritage significance of the house and the late Mr Lee's thinking and wishes in relation to it.

But Mr Lee Hsien Yang questioned why this was necessary, since the Government had said it would not be making a decision on the house as long as Dr Lee was residing there. "Wei Ling is there today. She has no intention to move out. Why is this committee in existence?" he said.

To this, Mr Tan said the committee had made it clear to Dr Lee and Mr Lee Hsien Yang that the Government has no intention of doing anything with the house as long as Dr Lee continues to reside there.

In his statement, Mr Tan also said the committee had asked Dr Lee and Mr Lee Hsien Yang questions on how their father's will was prepared, and the role played by Mrs Lee Suet Fern and lawyers of her firm in preparing it.

Mr Lee Hsien Yang told The Straits Times the will was prepared by his cousin Kwa Kim Li, a lawyer at Lee & Lee, the firm his father and mother, Madam Kwa Geok Choo, had co-founded in 1955.

He added that his wife had only prepared the words of his father's wish to have the house demolished.

He also said the committee should not be looking at a will which has been deemed valid by the court in probate: "A will in probate is beyond doubt and is the established and binding will of an estate."

He added that he and Dr Lee felt strongly about the house being demolished as they wanted to honour their late parents' wishes.

"Both my parents wanted it, we feel we owe a duty to honour our parents' wishes. My parents asked this of all three children and they told this to us many times in our lives. It is the least we could do for them, and actually I think many people would like to see that wish fulfilled," he told The Straits Times.

PM Lee said in a statement yesterday he was disappointed his siblings had chosen to publicise private family matters.

"While siblings may have differences, I believe that any such differences should stay in the family. Since my father's passing in March 2015, as the eldest son I have tried my best to resolve the issues among us within the family, out of respect for our parents," he said.

Correction: A quote in the story has been corrected to change a word that was misheard.