President Trump last week defended a widely denounced plan to bus migrants to sanctuary cities — but the New York Times reported Sunday that the move was partly a distraction tactic.

With the Mueller report set to be released this week, Trump and his allies are reportely working to seize the initiative and take the sting out of any potentially damaging but previously unreported findings.

In his controversial summary of the report to lawmakers, Attorney General William Barr said that Mueller's probe did not establish Trump's campaign colluded with Russia, and brought no obstruction charges.

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President Donald Trump's threats to send migrants to sanctuary cities were part of a ploy to distract attention from the impending release of the Mueller report, sources close to the president told the New York Times in a report published Sunday.

Trump last week defended plans to send migrants to Democratic Party-run sanctuary cities — those which have passed legislation or have policies in place designed to limit cooperation with federal immigration laws and the deportation of undocumented migrants.

That defence, the New York Times wrote Sunday, was partly a ploy to whip up controversy and distract from the Mueller probe.

Trump's own administration had resisted the policy, which has been criticised as potentially illegal by Democratic opponents.

Sources close to the president told the Times that he is purposefully escalating his language to rally his base supporters and anger political opponents and the media.

In a tweet Saturday, the president tweeted that the USA "has the absolute legal right to have apprehended illegal immigrants transferred to Sanctuary Cities."

Read more: Trump official blames 'deep state' bureaucrats for foiling president's bid to throw out asylum rules

After Attorney General William Barr released a summary of Mueller's report March 24, Trump hailed it as a "complete and total exoneration" of him, following accusations that his campaign colluded with Russia to win the 2016 election, and that he obstructed justice to hamper investigators.

But the Times reported on Sunday that close aides of the president wish he would back away from the claim of exoneration, with the full report expected to contain damaging information for the administration when released in a redacted form by Barr at some point this week.

In his summary of the report to Congress, Barr wrote that Mueller's investigators did not establish that the Trump campaign conspired with Russia in 2016 – but also noted that while this report does not conclude the President committed a crime, it also does not exonerate him.

The special counsel declined to reach a conclusion on whether Trump should be charged with obstruction, but Barr said the evidence presented in the report did not warrant bringing the charge.

Mueller probe officials, however, have expressed concern that the attorney general's summary presents the report in a better light for the president than is warranted by the facts, reported the Washington Post.

It is expected that the full Mueller report will be released in redacted form at some point this week. Alex Wong/Getty

Read more: Trump officials desperate to toughen border policies reportedly want to offer migrant families a choice: Get locked up together or risk not seeing your child for years

In a bid seize the initiative, Trump and his allies have launched an attack on the FBI agents who instigated the Mueller probe, with Barr telling lawmakers last week the Trump campaign was spied on in 2016. Barr said he had ordered an investigation into the origins of the Russia probe.

In an early morning tweet Monday, the president kept up the attacks on the investigators behind the probe.

"Mueller, and the A.G. based on Mueller findings (and great intelligence), have already ruled No Collusion, No Obstruction. These were crimes committed by Crooked Hillary, the DNC, Dirty Cops and others! INVESTIGATE THE INVESTIGATORS!" tweeted Trump.