Robert Trump, the younger brother of President Donald Trump, has passed away, the White House said in a statement late Saturday.

“It is with heavy heart I share that my wonderful brother, Robert, peacefully passed away tonight,” the president said in the statement. “He was not just my brother, he was my best friend. He will be greatly missed, but we will meet again.”

There were conflicting reports about whether he was 71 or 72, according to NBC News. 

The president traveled to New York City on Friday to visit his ailing younger brother who was back in hospital.

It is not clear what the cause of his death was. The White House did not disclose Robert Trump’s illness and the date of his most recent hospitalization.

He was one of Trump’s four siblings and recently filed a lawsuit to block the publication of a book by their niece, Mary Trump. The tell-all memoir, “Too Much and Never Enough, How My Family Created the World’s Most Dangerous Man,” was published ahead of schedule after Robert failed to stop its release.

Robert Trump argued that Mary Trump violated a nondisclosure agreement she signed with him, Donald Trump and their sister.

Ivanka Trump, the president’s daughter and a senior White House advisor, said on Twitter: “Uncle Robert, we love you. You are in our hearts and prayers, always.”

Her brother Eric Trump called their uncle “an incredible man – strong, kind and loyal to the core.”

Former New York Mayor Rudy Giuliani also tweeted his condolences.

“Robert Trump has a big heart. As a former Mayor I know how much he did to help New Yorkers in need. We have lost a really good man. My love, prayers and condolences to the #Trump family,” Giuliani said on Twitter.

Here is the full statement from the White House.

— CNBC’s Dan Mangan contributed to this report.