US President Donald Trump’s younger brother Robert Trump, 71, died on Saturday. Robert was being treated in a New York hospital for several days. US Media had reported that he was seriously ill, however, the cause of death is still unknown.

“He was not just my brother, he was my best friend. He will be greatly missed, but we will meet again. His memory will live on in my heart forever. Robert, I love you. Rest in peace,” Donald Trump said in a statement. The US President had visited his ailing brother on Friday at the hospital, staying for about 45 minutes.

Born in 1948, Robert worked on Wall Street before joining the family’s real estate business.

Robert, youngest of the Trump siblings, was closest to the US President with Donald Trump once saying, he is probably the only guy whom he will call ‘honey.’ Trump has previously called his brother Robert “wonderful” and said they have “had a great relationship for a long time, from day one.”

“Uncle Robert, we love you. You are in our hearts and prayers, always,” Donald Trump’s daughter and adviser Ivanka said on Twitter. Her brother Eric said Robert Trump would be “deeply missed by our entire family.”

Robert was always a loyal supporter of his older brother, even though he never became an integral part of the Trump Organisation. “I support Donald 1000%,” Robert told the New York Post in January 2016 as Donald was making his bid for the White House.

Trump’s younger brother had also filed a lawsuit against their niece Mary to stop publication of her book, “Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man,” which paints Donald Trump as the product of a “toxic” family.

In his unsuccessful attempt, Robert argued that she was violating a non-disclosure agreement signed in 2001 after the settlement of her grandfather’s estate. Mary was the daughter of the eldest Trump brother Fred Trump Jr, who died of alcoholism in 1981.

Robert divorced his long-time wife Blaine in 2009 and in March this year married Ann Marie Pallan, a Trump Organization employee. The couple were living a quiet life at their home in Millbrook, the Hudson Valley, as per media reports.