A French archbishop has been found guilty of covering up child sexual abuse by a priest in his diocese in yet another crushing blow to the Catholic church’s credibility on the most damaging issue it has faced in recent history.

Cardinal Philippe Barbarin, the archbishop of Lyon, was given a six-month suspended prison sentence on Thursday for failing to report to the authorities accusations made against the priest.

Barbarin said he would submit his resignation to the pope within the next few days.

“The responsibility and guilt of the cardinal have been confirmed by this judgment. It’s an extraordinary symbol, a moment of huge emotion,” a lawyer for the victims, Yves Sauvayre, said after the verdict.

François Devaux, who leads a victims’ group in Lyon, said Barbarin’s conviction was a “major victory for child protection”. He added: “We see that no one is above the law. We have been heard by the court. This is the end of a long path.”

Barbarin’s lawyer said his client would appeal against the verdict, which followed a trial this year. “This is a decision that is not fair at the juridical level,” Jean-Felix Luciani said. “We hope that at the next step, justice will be done.”

There was no immediate response to the verdict from the Vatican.

Barbarin, the highest-profile French Catholic cleric to face trial in relation to sexual abuse, was not in court to hear the verdict. Five other defendants were acquitted.

The archbishop’s conviction came nine days after it was disclosed that Cardinal George Pell, until recently the third most powerful man in the Vatican and former archbishop of Melbourne and Sydney, had been convicted of sexual abuse.

Pell is being held in solitary confinement as an at-risk prisoner in the run-up to his sentencing next week. An appeal against his conviction is expected to be heard in June.

Last month, another high-profile figure was defrocked by the pope after a Vatican hearing found him guilty of sexually abusing minors.

Pope Francis had been accused of failing to investigate or take action over Theodore McCarrick, a former cardinal and archbishop of Washington, despite years of rumours about his predatory behaviour with trainee priests.

An unprecedented summit at the Vatican of cardinals, bishops and other senior church figures on sexual abuse last month ended with the pope calling for an “all-out battle” to erase it “from the face of the earth”. But survivors were disappointed that few concrete measures emerged from the four-day meeting.

At his trial in January, Barbarin told the court in Lyon he had “never sought to hide, much less cover up these horrible acts”.

The scandal in Lyon emerged in 2015 when a former Scout went public with allegations that a local priest, Bernard Preynat, had abused him as a child 25 years earlier.

Devaux also filed a complaint against Barbarin, the priest’s superior, alleging he had known about the abuse and covered it up.

After a six-month inquiry and 10 hours of interviews with Barbarin, investigators dropped the case in 2016, saying the allegations against him were either too old or impossible to prove.

But a group of victims succeeded in having the case reopened, which led to Barbarin and others, including the archbishop of Auch and the bishop of Nevers in France, standing trial.

The head of the Vatican’s powerful Congregation for the Doctrine of the Faith, the Spanish archbishop Luis Francisco Ladaria Ferrer, was also accused of complicity in the alleged cover-up in Lyon. But the Vatican cited his immunity from prosecution to avoid a trial.

In correspondence with Barbarin about the priest, Ferrer advised the cardinal to take “necessary disciplinary measures while avoiding public scandal”.

The victims’ group received calls and testimony from 85 people claiming to have been victims of Preynat in Lyon.

After he was first denounced in 1991, the priest was prevented from leading Scout groups, but was later allowed to teach children and held positions of authority in parishes until the scandal became public in 2015.

Preynat has acknowledged abusing boys and is to be tried this year.

film based on testimonies from survivors of Preynat’s abuseBy the Grace of God, opened in French cinemas last month.

Two other senior French religious figures have previously been convicted of failing to report child abuse: the archbishop of Bayeux-Lisieux, Pierre Rican, in 2001, and the former bishop of Orléans, André Fort, last year.