US President Donald Trump's attorney Rudy Giuliani said on Sunday the president probably has the power to pardon himself but does not plan to do so.

Asked whether Trump has the power to give himself a pardon, Giuliani said, "He's not, but he probably does." Giuliani added that Trump has no intention of pardoning himself," but that the US Constitution, which gives a president the authority to issue pardons, "doesn't say he can't."

Giuliani said on ABC's "This Week" program, "It would be an open question. I think it would probably get answered by, gosh, that's what the Constitution says."

Giuliani also said it is an "open question" whether Trump would sit for an interview with Robert Mueller, the special counsel investigating potential collusion between Trump's 2016 presidential campaign and Russia, but that the president's lawyers were leaning against having him testify.

Mueller is also looking into whether Trump unlawfully sought to obstruct the Russia investigation.

House Republican Majority Leader Kevin McCarthy said on CNN on Sunday that no president should pardon himself.

Trump's lawyers argued in a letter to the special counsel that the president could not have obstructed the probe given the powers granted to him by the Constitution, the New York Times reported on Saturday.

In the January 29 letter, Trump's lawyers contended that the Constitution gives the president the power to "terminate the inquiry, or even exercise his power to pardon," the Times reported.