A US federal judge has agreed to delay former national security adviser Michael Flynn’s sentencing so he can continue cooperating with the Russia probe.

Attorneys for Flynn had asked District Judge Emmet Sullivan to postpone the sentencing. The judge will hold a review conference in March.

The request came after Judge Sullivan warned Flynn that if he were sentenced as scheduled on Tuesday, he might not get all the credit for his cooperation with investigators that he is entitled to.

Flynn pleaded guilty to lying to the FBI about his Russia contacts. Prosecutors had recommended no prison time, citing his cooperation. But the judge’s rebuke raised the prospect that Flynn could get a harsher sentence.

Michael Flynn
Michael Flynn (Carolyn Kaster/AP)

Judge Sullivan earlier lashed out at Donald Trump’s first national security adviser, saying “I can’t hide my disgust, my disdain” at his crime.

“Arguably you sold your country out,” he said.

Flynn, who served as national security adviser for only a few weeks, will be the first White House official sentenced in special counsel Robert Mueller’s investigation into possible co-ordination between Russia and the Trump campaign.

The hearing took place amid escalating legal peril for the president, who was implicated by federal prosecutors in New York this month in hush-money payments to cover up extramarital affairs.

Nearly half a dozen former aides and advisers — including Flynn — have pleaded guilty or agreed to co-operate with prosecutors.

Mr Trump signalled his interest in the case by tweeting “good luck” to Flynn hours before the sentencing hearing.

He added: “Will be interesting to see what he has to say, despite tremendous pressure being put on him, about Russian Collusion in our great and, obviously, highly successful political campaign. There was no Collusion!”

Judge Sullivan told Flynn he would take into account his extensive co-operation with the government, which includes 19 meetings with investigators as well as a 33-year military career that included service in Iraq and Afghanistan.

But he also said he was forced to weigh other factors including Flynn’s decision as national security adviser to lie to the FBI on the premises of the White House about contacts he had with the Russian ambassador to the US.