Special counsel Robert Mueller's team has informed U.S. President Donald Trump's legal team that it would follow Justice Department guidance and not seek an indictment against Trump, according the president's lawyer Rudy Giuliani.

"They can't indict. At least they acknowledged that to us after some battling. They acknowledged that to us," Giuliani told CNN on Wednesday. "All they get to do is write a report."

Analysts say that the conclusion is likely based on longstanding guidelines by the Justice Department, but not about any assessment of the evidence the special counsel's team has found.

The precedent that federal prosecutors cannot indict a sitting president is laid out in a 1999 Justice Department memo, but it has never been tested in court.

An absence of an indictment would not necessarily mean that Trump is in the clear. Mueller could submit a report making referrals or recommendations to the House of Representatives, which could decide what to do about the report and whether to pursue articles of impeachment.

During his interview with CNN, Giuliani also said that he will use the Mueller probe's one-year mark, which is Thursday, to rachet up pressure on the investigation.

Mueller was appointed as the special counsel to lead the Russia probe on May 17, 2017, days after Trump fired then FBI Director James Comey.

The year-long investigation is looking into alleged links between the Trump campaign and Moscow, Russian interference with the 2016 U.S. presidential election, and whether Trump asked Comey to end the probe into former national security adviser Michael Flynn, among other things that would arise from the investigation.

Trump has repeatedly denied allegations of collusion, describing the Russia probe as a "hoax" or a "witch hunt."

Mueller has so far charged 19 people, among whom were several Trump campaign associates that have pleaded guilty to various charges stemming from Mueller's investigation.

They are all cooperating with prosecutors but none of the charges are directly related to the collusion allegation.