Michael Cohen took a last swipe at President Donald Trump while reporting to federal prison on Monday to start a three-year sentence for crimes including tax evasion and campaign finance violations related to hush-money payments made to protect his former boss.

Cohen, who turned on Trump last summer after a decade as his personal lawyer, fixer and 'take a bullet' loyalist, didn't mention the president by name, but he left little doubt about whom he blamed for his incarceration.

'I hope that when I rejoin my family and friends that the country will be in a place without xenophobia, injustice and lies at the helm of our country,' Cohen told reporters outside his Manhattan apartment. 'There still remains much to be told, and I look forward to the day where I can share the truth.'

Cohen, 52, then stumbled through a crush of media, ignoring shouted questions, and got into a waiting Cadillac Escalade, which drove him to jail 115 kilometres northwest of New York City.

He got a slight jump on his prison sentence, arriving at the Federal Correctional Institution, Otisville, at around 11.45am, more than two hours before a court-imposed deadline.

The prison has a minimum-security camp that's become known for the white collar criminals it houses and the amenities — including tennis courts, bocce ball and rugelach in the commissary — that it affords them.

Cohen — officially Inmate No. 86067-054 — took off the blue blazer he wore on the ride up and left it with his driver before walking into prison, where he was to be provided with a khaki uniform.

The US Bureau of Prisons confirmed Cohen was in its custody but declined to provide details of his confinement, citing privacy and security rules.

At Otisville, officials took extra measures to deal with the intense media interest in Cohen's arrival. They put up concrete barriers along the two-lane road leading to the facility and deployed cones and caution tape to keep about two dozen reporters and photographers from getting too close.

Cohen had fought to delay or reduce his sentence but failed in a last-ditch effort to convince federal prosecutors that his cooperation in various investigations related to Trump warranted leniency.

Cohen's lawyer and spokesman, Lanny Davis, said Cohen would continue to be available to cooperate with law enforcement, though it's unclear how much his cooperation is wanted.

Since mid-March, federal prosecutors in New York have rebuffed Cohen's repeated offers to provide more information about alleged wrongdoing by Trump and other people in his orbit, Davis said.

His legal team asked House Democrats last month to intercede with prosecutors after Cohen testified on Capitol Hill in February and March, but they were reticent to do so.

'Michael may be sentenced within the walls of a federal correctional institution. But the truth has no walls,' Davis said in a statement Monday.

In an essay published on Sunday, a Trump Organisation executive wrote that Cohen was 'a bluffing, boasting New Yorker' who overstated his role at the company and that he only had himself to blame for going to prison.

Cohen had no real decision-making authority and was rather 'a lone wolf constantly seeking the boss's approval and fearing others would take his credit,' George Sorial wrote in The Wall Street Journal.

Cohen is the only person charged with a crime in connection with the hush-money payments to women who allegedly had affairs with Trump.

Federal prosecutors have said Trump directed Cohen to arrange the payments to buy the silence of porn actress Stormy Daniels and former Playboy model Karen McDougal in the run-up to the 2016 election. Trump denies having trysts with either woman.

Cohen also pleaded guilty to lying to Congress about a Trump Tower project in Moscow, to bank fraud, and to tax evasion charges that stemmed, not from his dealings with Trump, but from his failure to report income from other business interests.

At Cohen's sentencing last December, his lawyer requested that he be placed at Otisville, which Forbes once ranked as one of 'America's 10 Cushiest Prisons.' He was originally scheduled to start his sentence in March, but a judge granted a two-month delay so he could recover from surgery and get his affairs in order.

Cohen will spend the first few weeks of his sentence in admission and orientation. He'll undergo medical and mental health screenings and be assigned a job, such as mowing the grounds or cleaning up the visiting room. If he wants to work on a tell-all, he'll have to skip sleep or exercise to do so.

'There's no free time to work on your book, or whatever,' said former Otisville employee Don Drewett.

Cohen's fellow inmates include s'Jersey Shore' star Mike 'The Situation' Sorrentino, who wraps up an eight-month tax fraud sentence in September. But Cohen should avoid acting like he's still in spotlight, said Jack Donson, a former Otisville case manager who advises white-collar criminals on what to expect in prison.

'You assume the role of an inmate,' said Donson. 'You're cordial to everybody. You're respectful to everybody. You do your time. You ask for nothing from staff. Nothing from inmates. You accept nothing from inmates. You're nobody. Seriously.'

If Cohen can't adjust, Donson said, 'his time is going to be miserable.'