ROME (Reuters) - Pope Francis washed and kissed the feet of 12 prisoners on Thursday at a traditional service, telling them to shun any inmate hierarchy structure or law of the strongest and to help each other instead.

Francis’ predecessors held the traditional Holy Thursday rite in one of Rome’s great basilicas, washing the feet of 12 priests. But to emphasise its symbolism of service, Francis transferred it to places of confinement, such as prisons, immigrant centres or old age homes.

He travelled this year to a prison in the town of Velletri, about 40 km south of Rome.

It is the fifth time since his election in 2013 that he has held the service, which commemorates Jesus’ gesture of humility toward his apostles on the night before he died, in jail.

Francis told the inmates that in Jesus’s time, washing the feet of visitors was the job of slaves and servants.

“This is the rule of Jesus and the rule of the gospel. The rule of service, not of domination or of humiliating others,” he said.

“Among you, it must not be this way (domination). The strongest must serve the smallest one. The one who thinks he is the strongest must be a servant. We must all be servants,” he said.

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Of the male inmates whose feet Francis washed, there were nine Italians, one Brazilian, one Moroccan and one Ivorian. The Vatican did not give their religions.

In the past, conservative Catholics criticised the pope for washing the feet of women and Muslim inmates.

The Velletri prison, which is overcrowded like most Italian jails, mostly holds foreigners for common crimes, but one section holds turncoats who collaborated with investigators and get special protection.

On Good Friday, Francis, marking his seventh Easter season as Roman Catholic leader, is due to lead a Via Crucis (Way of the Cross) procession around Rome’s ancient Colosseum.

The 82-year-old leader of the world’s 1.3 billion Roman Catholics leads an Easter vigil service on Saturday night and on Easter Sunday reads the traditional “Urbi et Orbi” (To The City and The World) message.