The Democratic presidential candidate Bernie Sanders has said Pope Francis is a socialist, just like him.

The current runner-up for the Democrat nomination has been a long-standing fan of the Argentinian pontiff but comments in an interview with the Catholic network Salt and Light mark a step further than any previous accolade.

"[What] it means to be a socialist, in the sense of what the Pope is talking about, what I'm talking about, is to say that we have got to do our best and live our lives in a way that alleviates human suffering, that does not accelerate the disparities of income and wealth," Sanders told Rev Thomas Rosica, head of Salt and Light, in an interview to be broadcast Tuesday evening.

When Rosica asked the left-wing candidate if he thought Francis was a socialist, Sanders said he did.

"When [the Pope] talks about wealth being used to serve people, not as an end in itself, I agree with that," he said.

The interview was filmed last September, on the eve of Francis's first trip to the US but Rosica said "the timing was right [to broadcast] now", according to RNS.

However the Pope has been keen to distance himself from accusations of left-wing leaning by more conservative wings of the Catholic Church.

"I am certain I have never said anything more than what is in the social doctrine of the church," Francis told reporters shortly before landing in the US in September. "I follow the church and in this I do not think I am wrong.

"Maybe I have given an impression of being a little bit to the left," the Pope said. "But if they want me to recite the creed, I can!"

The Toronto-based Catholic network released a statement distancing itself from Sanders' views, saying they do not reflect the views of the media foundation.

"We are aware that certain views held by Senator Sanders oppose the moral teachings of the Catholic Church," the statement read. "As a Catholic media foundation, Salt and Light does not share these views, denounces his positions as such, but recognizes the Senator's right to hold them.

"We recognize that respectful and charitable dialogue, especially with those who fundamentally disagree with certain or all aspects of the Church's teachings, is the appropriate Christian approach in dealing with complex social and political issues."

Indeed Sanders admitted on areas such as abortion and gay rights, "we just have to disagree".

"[The] best that I can say on those issues is let's respect each other when we disagree, and let's work together on those areas that we do agree on," he said.

"I will be very clear about my disagreements with the [Catholic] Church, but I think that the Pope is playing an historical role coming at exactly the right moment in human history, where his voice is having a profound impact, not only on our country, but all over the world."

However he was keen to praise the Pope on his criticism of the world's "massive income wealth inequality" and the "idolatry of money".

"It's not just, oh, isn't it important to talk about the poor, and the homeless, and the unemployed," said the candidate.

"Yeah it is, but he [Pope Francis] goes deeper than that. And he talks about how we should not simply be spending our lives trying to make more and more money, and turning our backs on those people most in need, and that strikes me very deeply."