SANFORD, Fla. — Republican presidential nominee Donald Trump said Tuesday that President Obama ought to be investigated over Hillary Clinton’s private email server, claiming that emails just made public show that he knew about its existence before the public did.

But nothing in the emails Trump used as the basis for his allegation demonstrates that Obama knew about Clinton's server.

In an interview with Reuters, Trump said Obama “knew all about her private server,” and, “this means that he has to be investigated.”

Shortly after the interview was published, Trump reiterated his claim about Obama at an outdoor rally held at an airport here.

“President Obama claimed to have no knowledge whatsoever of Clinton’s illegal email server,” Trump said, later adding, “but newly public emails — WikiLeaks — prove otherwise.” After an FBI investigation, Clinton was not charged with any crimes over her email use as secretary of state.

Trump read a published email exchange involving Clinton aides that he said implicated the president. “That means Obama is now into the act,” Trump said.

An email released by the anti-secrecy group WikiLeaks on Tuesday shows that Clinton adviser Cheryl Mills expressed displeasure after Obama told CBS News in March 2015 that he had learned about Clinton's email system “the same time everybody else learned it through news reports.”

"[We] need to clean this up — he has emails from her — they do not say,” Mills wrote to Clinton campaign chairman John Podesta, indicating that Obama certainly knew of Clinton's private address because he had corresponded with her using it.

Two days later, White House press secretary Josh Earnest clarified to reporters that Obama had not been trying to say he did not know Clinton's address but instead that he was “not aware of the details of how that email address and server had been set up, or how Secretary Clinton and her team were planning to comply with the Federal Records Act.”

On Tuesday, Earnest reiterated that Obama had known Clinton's address but had been unaware of “any knowledge of where her server was located or what sort of arrangements had been made to store her email.”

The Clinton campaign has refused to authenticate the emails, citing U.S. intelligence findings that the Russian government orchestrated recent hacks of Democratic Party email accounts. However, nothing in the release proves that Obama knew about Clinton's server, as opposed to her use of a private account.

 Helderman reported from Washington.