Pope Francis has delivered an impromptu critique to members of his own church, suggesting it would be better for some to be atheist than Catholic.

The Argentinian pontiff rebuked those who lived a "double life" by pretending to be Christians, but lived out values opposed to the teachings of the bible.

Speaking at the private morning mass from his residence in Vatican City on Thursday (23 February), the 80-year-old said: "It is a scandal to say one thing and do another. That is a double life.

"There are those who say, 'I am very Catholic, I always go to mass, I belong to this and that association, but my life is not Christian. I don't pay my workers a just wage, I exploit people, I am dirty in my business, I launder money."

"This is a double life and so many Christians are like this, and they cause scandal.

"How many times have we heard, all of us, around the neighbourhood and elsewhere, 'but to be a Catholic like that, it's better to be an atheist?' It is that – a scandal."

The Pope said those who lead lives like that would be caught out at their day of reckoning.

"You will arrive in heaven and you will knock at the gate," he said, according to Vatican Radio transcript.

"Here I am, Lord, but don't you remember? I went to Church, I was close to you, I belong to this association, I did this. Don't you remember all the offerings I made?

"Yes, I remember the offerings, I remember them: all dirty, all stolen from the poor. I don't know you."

"That will be Jesus's response to these scandalous people who live a double life."

The Pope's surprise message comes as the Vatican is engulfed in a corruption scandal over allegedly money laundering charges, involving millions of Euros.