Donald Trump condemned as "disgraceful" a leak of dozens of questions Robert Mueller wants to ask the US president in a face-to-face interview.
Mr Mueller, the special counsel appointed to investigate Russian meddling in the 2016 US election, submitted more than 40 proposed questions to Mr Trump’s lawyers.
The questions indicated he wants to focus on whether Mr Trump attempted to obstruct justice by blocking the probe, and any links between his campaign and Russia.
Mr Mueller’s team read the inquiries over the telephone to Mr Trump’s lawyers who compiled them into a list.
That list was then leaked to the New York Times by "a person outside Mr Trump’s legal team," the newspaper said.
Mr Trump, writing on Twitter, said: "So disgraceful that the questions concerning the Russian Witch Hunt were ‘leaked’ to the media.
However, the list did suggest that Mr Mueller is looking into whether Mr Trump’s campaign coordinated in any way with the Kremlin, and whether he knew about it.
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Many of the questions were predictable, based on events that are already publicly known, but one appeared to stem from as yet unreleased information.
In it Mr Mueller asked: "What knowledge did you have of any outreach by your campaign, including by Paul Manafort, to Russia about potential assistance to the campaign?"
There has been no public suggestion so far of alleged outreach by Mr Manafort, who has been separately charged by Mr Mueller with financial crimes.
Mr Mueller’s questions gave no indication whether Mr Trump is an official suspect in his year-long investigation, which has been shrouded in secrecy.
The numerous inquiries related to potential obstruction of justice included whether Mr Trump had sought to fire Mr Mueller himself.
They also included what Mr Trump’s intentions were in firing James Comey as FBI Director, and whether he initially appointed Jeff Sessions as attorney general to "protect" himself from any Russia investigation.
In relation to Russia links Mr Mueller wants to ask Mr Trump when he became aware of a Trump Tower meeting in June 2016 between senior members of his campaign and a Russian lawyer who offered "dirt" on Hillary Clinton.
The special counsel also expressed interest in Mr Trump’s trip to Moscow for the Miss Universe pageant in 2013, and any discussions he had during the campaign about meeting Vladimir Putin.
Mr Mueller intends to ask Mr Trump about the dossier compiled by former MI6 officer Christopher Steele.
Mr Comey briefed the president about the dossier privately on Jan 6, 2017.
One of Mr Mueller’s questions reads: "What was your reaction to Mr Comey’s briefing that day (Jan 6, 2017) about other intelligence matters?"
The dossier included an allegation of an encounter involving Mr Trump and prostitutes in Moscow in 2013, which the president has vehemently denied.
Mr Trump’s businesses also feature in the questions, including any discussions he had with Michael Cohen, his personal lawyer, about a potential property deal in Moscow.
Mr Mueller also wants to ask if Mr Trump offered a future presidential pardon to Michael Flynn, his former national security adviser, who has already been criminally charged with lying to the FBI over his Russia contacts.
The president has expressed a desire to sit down with Mr Mueller for an interview, believing it could hasten the conclusion of an investigation he has repeatedly called a "witch hunt".
However, his own legal team has been divided, with some of his lawyers suggesting the president could be opening himself up to a "perjury trap" by answering open-ended questions from Mr Mueller.
The questions were provided by Mr Mueller’s team in March and convinced John Dowd, Mr Trump’s lead lawyer at the time, that the president should not agree to an interview.
Mr Dowd resigned shortly afterwards amid suggestions his client was determined to ignore his advice.
Two weeks ago Rudy Giuliani, the former New York mayor, joined Mr Trump’s legal team.
Mr Giuliani said he is trying to establish whether Mr Mueller’s team would be "truly objective" in an interview.
Neither Mr Trump’s legal team, nor Mr Mueller’s office have commented on the leaking of the questions.