Pope Francis has called on Catholic leaders to seek a ban on the death penalty exclaiming that 'Thou shall not kill applies to the guilty as well as the innocent'.

Speaking to thousands at St. Peter's Square, in the Vatican, the Pontiff asked politicians around the world to make 'a courageous and exemplary gesture' during the Church's current Holy Year.

He said: 'I appeal to the consciences of those who govern to reach an international consensus to abolish the death penalty.

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Execution ban: Pope Francis has called for Catholic leaders to ban the death penalty during a speech at St. Peter's Square, in the Vatican, today

Thousands flocked to St. Peter's Square to hear the Pope speak about the death penalty and conditions for prisoners earlier today. His comments came prior to a conference on the issue in Rome this week

'The commandment 'You shall not kill,' has absolute value and applies to both the innocent and the guilty.'

The 1.2 billion-member Catholic Church allowed the death penalty in extreme cases for centuries, but the position began to change under the late Pope John Paul, who died in 2005.

The pope added that there was now 'a growing opposition to the death penalty even for the legitimate defence of society' because modern means existed to 'efficiently repress crime without definitively denying the person who committed it the possibility of rehabilitating themselves.'

Francis made the comments to throw his weight behind an international conference against the death penalty starting on Monday in Rome and organised by the Sant'Egidio Community, a worldwide Catholic peace and justice group.

Catholic faithfuls are given rosary beads by a nun in St Peter's Square during the Pope's speech today

Francis, who has visited a number of jails since his election as pope nearly three years ago - the latest in Mexico last week - also called for better prison conditions.

He said: 'All Christians and men of good will are called on to work not only for the abolition of the death penalty, but also to improve prison conditions so that they respect the human dignity of people who have been deprived of their freedom.'