OUTGOING US President Barack Obama has denied freedom to Native American political prisoner Leonard Peltier, his lawyer said on Wednesday night.

Broadcaster Democracy Now! was the first to break the news in an interview with Martin Garbus, attorney for the American Indian Movement member imprisoned since 1976.

The Office of the Pardon Attorney wrote to Mr Garbus earlier on Wednesday to inform him that Mr Peltier would not receive a presidential pardon or have his sentence or commuted before Mr Obama leaves office today.

In response to his petition for clemency, the office wrote: “The decision was reached that favourable action is not warranted. “Under the constitution, there is no appeal from this decision.”

Mr Peltier’s supporters had been optimistic following Mr Obama’s announcement on Tuesday of early release for military whistleblower Chelsea Manning and Puerto Rican independence struggle leader Oscar Lopez.

“I think it’s fair to say that if he doesn’t get commuted by President Obama, he’ll die in jail,” Mr Garbus said.

“He’s a very sick man. So, Obama’s not granting him clemency is like a sentence of death. [President-elect Donald] Trump ain’t going to do it.

“He’s not going to live past that time. I don’t want to be negative, but that’s the reality. He’s very sick and he’s been in prison over 40 years, hard years, six years of solitary.”

Mr Peltier is serving two consecutive life sentences for the 1975 murder of two FBI agents on the Pine Ridge Oglala Lakota reservation in South Dakota, though he has always protested his innocence.

His case has become a cause celebre for left-wing and civil rights campaigners.

Despite providing several alibis and his car not matching the description of the vehicle from which the two agents radioed that they under fire before their deaths, Mr Peltier was convicted in 1976.

Several prosecution witnesses later recanted their initial statements to police, saying they had been obtained under duress.

Fellow accused Robert Robideau and Darrelle “Dino” Butler were acquitted at an earlier trial while Mr Peltier was still a fugitive.

He escaped from California’s Lompoc federal prison in 1979 but was recaptured three days later.

Amnesty International USA executive director Margaret Huang said: “We are deeply saddened by the news that President Obama will not let Leonard go home.”