WASHINGTON, DC (AP) — Special counsel Robert Mueller said yesterday that he was legally barred from charging President Donald Trump with a crime but pointedly emphasised that his Russia report did not exonerate the president. If he could have cleared Trump of obstruction of justice he “would have said so”, Mueller declared.

The special counsel’s remarks, his first in public since being tasked two years ago with investigating Russian interference to help Trump win the 2016 presidential election, stood as a strong rebuttal to Trump’s repeated claims that he was exonerated and that the inquiry was merely a “witch hunt”. They also marked a clear defense to criticism, including by Attorney General William Barr, that he should have reached a determination on whether the president illegally tried to obstruct the probe by taking actions such as firing his FBI director.

Mueller made clear he believed he was restrained from indicting a sitting president — such an action was “not an option”. He did not use the word ‘impeachment” but said it was Congress’ job to hold the president accountable for any wrongdoing.

“If we had had confidence that the president clearly did not commit a crime, we would have said so,” Mueller said. “We did not, however, make a determination as to whether the president did commit a crime.”

Mueller’s statement largely echoed the central points of his 448-page report released by the Justice Department last month with some redactions. But his remarks, delivered at the department, were nonetheless extraordinary given that he had never before discussed or characterised his findings and had stayed mute during two years of feverish public speculation.

Mueller, a former FBI director, said his work was complete and he was resigning to return to private life.

Under pressure to testify before Congress, he did not rule it out. But he seemed to warn lawmakers that they would not be pulling more detail out of him. His report is “my testimony”, he said, and he won’t go beyond what is written in it.

Trump, who has repeatedly and falsely claimed that Mueller’s report cleared him of obstruction of justice, modified that contention somewhat shortly after the special counsel’s remarks. He tweeted, “There was insufficient evidence and therefore, in our country, a person is innocent. The case is closed!”

His personal attorney, Jay Sekulow, said that Mueller’s announcement “puts a period on a two-year investigation that produced no findings of collusion or obstruction by the president”.

Mueller’s comments, one month after the public release of his report on Russian efforts to help Trump defeat Democrat Hillary Clinton, appeared intended to both justify the legitimacy of his investigation against complaints by the president and to explain his decision to not reach a conclusion on whether Trump had obstructed justice.

Indicting Trump, he said firmly, was “not an option” in light of a Justice Department legal opinion that says a sitting president cannot be charged. But, he said, the absence of a conclusion should not be mistaken for exoneration.

“The opinion says the Constitution requires a process other than the criminal justice system to formally accuse a sitting president of wrongdoing,” Mueller said, referring to the Justice Department legal opinion. That would shift the next move, if any, to Congress, and the Democratic chairman of the House Judiciary Committee, which would investigate further or begin any impeachment effort, commented quickly.

New York Rep Jerrold Nadler said it falls to Congress to respond to the “crimes, lies and other wrongdoing of President Trump — and we will do so”.

On the other hand, Lindsey Graham of South Carolina, the Republican chairman of the Senate Judiciary Committee, said that Mueller “has decided to move on and let the report speak for itself. Congress should follow his lead”.

Trump has blocked House committees’ subpoenas and other efforts to dig into the Trump-Russia issue, insisting Mueller’s report has settled everything.

That report found no criminal conspiracy between the Trump campaign and Russia to tip the outcome of the 2016 presidential election in Trump’s favour. But it also did not reach a conclusion on whether the president had obstructed justice.

Barr has said he was surprised Mueller did not reach a conclusion on whether the president had criminally obstructed justice, though Mueller in his report and again in his public statement Wednesday said that he had no choice. Barr and Deputy Attorney General Rod Rosenstein decided on their own that the evidence was not sufficient to support an obstruction charge against Trump.

Barr, who is currently in Alaska for work and was briefed ahead of time on Mueller’s statement, has said he asked Mueller if he would have recommended charging Trump “but for” the legal opinion from the Office of Legal Counsel, and that Mueller ssaid “no”.

“Under long-standing department policy, a president cannot be charged with a federal crime while he is in office,” Mueller said. “That is unconstitutional. Even if the charge is kept under seal and hidden from public view that, too, is prohibited.”

Mueller, for his part, complained privately to Barr that he believed a four-page letter from the attorney general summarising the report’s main conclusions did not adequately represent his findings. Barr has said he considered Mueller’s criticism to be a bit “snitty.”