The Vatican said Friday that next week it will publish the results of a long-awaited investigation into ex-US cardinal Theodore McCarrick following his expulsion last year for sexual abuse.

Pope Francis had promised in 2018 to make a "thorough" investigation of how McCarrick, now 90, rose through the ranks despite years of allegations about sexual misconduct.

McCarrick was finally stripped of his cardinal's title in 2018 and his priest's status in 2019, after being found guilty by the Vatican of the sexual abuse of a teenage boy in the 1970s, and of sexual misconduct with adult male seminarians.

The former cardinal, who played a key role in raising funds for the Holy See from wealthy US donors, became the highest-ranking Church figure to be expelled in modern times.

Francis has promised a policy of "zero tolerance" for even high-ranking church members following a global scandal over paedophile priests, which has seen victims come forward from countries including Australia, Chile and Germany as well as the United States.

In the latest development in the global scandal, the Holy See's embassy in Poland on Friday announced sanctions against a 97-year-old cardinal.

An investigation will soon be published into how US cardinal Theodore McCarrick rose through the Church's ranks despite sexual abuse allegations
An investigation will soon be published into how US cardinal Theodore McCarrick rose through the Church's ranks despite sexual abuse allegations GETTY IMAGES NORTH AMERICA / CHIP SOMODEVILLA

Henryk Gulbinowicz was banned from public ministry and from using bishops' insignia following an unspecified investigation that local media said was related to alleged abuse.

Francis admitted the probe into McCarrick, which involves an extensive search through Vatican archives, could fuel accusations the Catholic Church has covered up abuse and protected predators for decades.

But the pontiff, who last year passed a landmark measure to oblige those who know about sex abuse in the Church to report it to their superiors, vowed to "follow the path of truth, wherever it may lead".

Victim support groups have been calling for the findings of the McCarrick report to be made public amid expectations that they could be explosive.

Fresh allegations against the former cardinal also emerged in the US last year.

Pope Francis embraces McCarrick in 2015
Pope Francis embraces disgraced priest McCarrick in 2015 POOL / Jonathan Newton

The Vatican said the report on the institutional knowledge and decision-making of the Holy See relating to McCarrick would be published on November 10 at 1300 GMT.

The four US dioceses where he served -- New York, New Jersey's Metuchen, Newark, and Washington DC -- are also thought to have contributed to the investigation.

It was launched after allegations by the Vatican's former ambassador to the US, Archbishop Carlo Maria Vigano, that senior Vatican officials had known since 2000 that McCarrick would invite seminarians to his beach house for sex.

But McCarrick was still made cardinal in 2001.

Vigano also claimed that former Pope Benedict XVI imposed sanctions on the cardinal in 2009 or 2010 -- but that Francis then lifted them.

The Vatican has refused to respond in detail to the allegations made by Vigano, a leading anti-Francis voice, who said he had warned the Argentine pontiff about McCarrick shortly after his election in 2013.

The measures against cardinal Gulbinowicz state that he cannot be buried in a cathedral, and that he would have to give some money to a foundation created by the Polish episcopacy to help victims of sexual abuse.

Gulbinowicz has been accused of abusing a 15-year-old in 1989 and protecting a priest who was branded a paedophile.

He is also accused of not having informed the Vatican about another priest who was found guilty of paedophilia.

This is the third such case this year in the higher echelons of Poland's ecclesiastical hierarchy.

Last month, the Vatican's ambassador to Poland announced the resignation of Polish bishop Edward Janiak who was suspected of covering up sexual abuse of children.

And in August, Pope Francis accepted the resignation of Slawoj Leszek Glodz, the Archbishop of Gdansk known for his high-end lifestyle and love of luxury, following accusations he had bullied priests and remained silent on alleged sex abuse.