His firing of Comey and the appointment of a special counsel to investigate his election campaign's ties to Russia last year have raised the question of whether he tried to squelch a probe into the alleged Russia connection.
Fanning the flames was a New York Times report that Trump had called Comey a "nut job" in a private meeting last week in the Oval Office with Russian Foreign Minister Sergei Lavrov and ambassador Sergei Kislyak. The Times quoted briefing notes of the conversation.
Asked for a response, the White House said that for national security reasons, "we do not confirm or deny the authenticity of allegedly leaked classified documents."
Russia's Interfax news agency on Saturday quoted Lavrov as saying he had not discussed Comey with Trump. "We did not touch this issue at all," the minister said.
In another development, the Washington Post said a current White House official close to Trump was a significant "person of interest" in the investigation into possible ties with Russia.A New York Magazine reporter later named the individual as Trump's son-in-law and close adviser Jared Kushner, but that information has yet to be independently verified.
The fallout followed Trump to Riyadh but did nothing to cool the welcome he received by the royal Saudi family.
King Salman bin Abdulaziz greeted Trump on a red carpet as he stepped off Air Force One, shaking the hand of his wife, Melania, and riding in the US presidential limousine.