Pope Francis has reiterated his call for the abolition of the death penalty and has also pleaded for the eradication of life imprisonment, which he described as a "hidden death penalty."

Speaking at a meeting of the International Association of Penal Law at the Vatican on October 23, the Pope pointed out that capital punishment should have gone with today's changing times.

"All Christians and people of goodwill are called today to fight not only for the abolition of the death penalty be it legal or illegal, in all of its form," said Francis.

"And this, I connect with life imprisonment," Francis said in his detailed discourse which also denounced human trafficking and corruption.

Amnesty International says 140 countries have abolished the death penalty. In 2013, 22 countries around the world were known to have carried out executions and at least 57 to have imposed death sentences.

Among countries that permit the death penalty are: Botswana, China, Egypt, Indonesia, Iran, Japan, Singapore, Syria, the United States and Zimbabwe.

Pope Francis also called for "the improvement of prison conditions in the respect of the human dignity of those who have been deprived of freedom," the Vatican news service reported.

Francis denounced what he called a "penal populism" that promises to solve society's problems by punishing crime instead of pursuing social justice.

"It is impossible to imagine that States today cannot make use of another means than capital punishment to defend peoples' lives from an unjust aggressor," Francis remarked before the representatives of the association.

'IMPROVE PRISON CONDITIONS'

"All Christians and people of good will are thus called....to improve prison conditions, out of respect for the human dignity of persons deprived of their liberty. And this, I connect with life imprisonment," he continued.

"Life imprisonment is a hidden death penalty," Francis stressed.

The Pope also condemned the continued detention of prisoners without trial, which he said accounted for more than half of those incarcerated in the world.

He said being detained at a prison can be viewed as a form of torture because detention is basically isolation from the external environment.

It can lead to "psychic and physical sufferings such as paranoia, anxiety, depression and weight loss and significantly increase the chance of suicide," he explained.

Pope Francis did not restrict his comments to law enforcers.

He also hit out at human trafficking and corruption, but noted such crimes "could never be committed without the complicity, active or passive, of public authorities."

"The corrupt one does not perceive his own corruption. It is a little like what happens with bad breath: someone who has it hardly ever realizes it; other people notice and have to tell him," the Pope said.

"Corruption is an evil greater than sin. More than forgiveness, this evil needs to be cured."