Pontiff in 'great pain' but said: 'Truth is the truth and we should not hide it'

Three priests and a religious education teacher have been arrested over the alleged abuse of altar boys by a Catholic paedophile ring in Spain.

The investigation was launched after one alleged victim wrote to Pope Francis claiming he was molested by a priest around ten years ago.

Francis said he felt 'great pain' after learning of the allegations but insisted that 'the truth is the truth and we should not hide it.'

He said he personally called the man, now 24, to offer his support and wrote to the Archbishop of Granada, Francisco Javier Martinez, urging him to launch an investigation.

The Archbishop of Granada, Francisco Javier Martinez (purple skullcap) lies prostrate with other priests in front of cathedral's high altar to ask forgiveness for alleged sexual abuse committed in the diocese. Three priests and a religious teacher have been arrested in Spain after a former altar boy claims he was abused

The Pope says he wrote to the Archbishop of Granada, Francisco Javier Martinez (purple skullcap), to urge him to launch an investigation into the claims that a former altar boy was molested by a priest (not pictured)

The group allegedly drew boys into their sphere of influence by taking them on as altar boys or assistants before molesting them.

A Granada judge is reportedly targeting 10 priests and two lay people, although only four have been arrested so far.

As they began appearing in court today, a second ex-altar boy filed a police report alleging he had also been abused, it was reported by The Local, which cited Spanish newspaper El País.

The four men were reportedly arrested at a chalet owned by the alleged head of the ring on Monday.

Officers confiscated two computers in the property but found contents had been deleted, it was claimed.

A police van containing a priest arrives at Granada's Court after being arrested on suspicion of child abuse

Speaking after returning to the Vatican from Strasbourg yesterday, he said the allegations were causing him 'great pain... but the truth is the truth and we should not hide it.'

The three Catholic priests and the teacher were arrested in Granada on Monday.

It was not clear when the man, now 24, had written to the Pope.

But investigations into the case started 'some time ago', Interior Minister Jorge Fernandez Diaz told reporters, without giving further details.

'Received news with great pain': Pope Francis said he personally called the alleged victim who claims he was molested by a priest around ten years ago when he was 14

The Pope said he told the man to 'go straight to the bishop tomorrow' after receiving the letter.

He added: 'I wrote to the bishop and told him to start an investigation.

'I received this news with great pain, very great pain, but the truth is the truth and we should not hide it.'

Pope Francis has promised a policy of zero tolerance for sexual abuse of minors by clerics after church scandals in several countries over many years.

However, groups representing victims say he has not done enough.