The late Polish pope John Paul II knew about child abuse in Poland's Catholic church years before becoming pontiff and helped cover it up, private broadcaster TVN reported Sunday.

Michal Gutowski, the investigator behind the broadcast, said that Karol Wojtyla, as he then was, knew of cases of paedophile priests within the church while still a cardinal in Krakow.

He transferred the priests to other dioceses -- one as far away as Austria -- to ensure no scandal ensued, he said.

Wojtyla, who was pope for 27 years from 1978 until his death in 2005, wrote a letter of recommendation for a priest accused of abuse to Vienna cardinal Franz Koenig, without mentioning the accusations, says Gutowski.

During his investigation, Gutowski says he spoke to victims of paedophile priests, their families and former church diocese employees.

He cites documents from the former Communist-era SB secret police and rare church documents to which he manage to get access.

But Gutowski said the Krakow diocese had refused him access to its own documentary archives.

The Polish church has in the past refused to provide documents to the judiciary or a public commission of enquiry investigating cases of church abuse of minors.

- Similar accusations -

One of Gutowski's sources said on condition of anonymity that he had personally told Wojtyla about acts of paedophilia concerning one priest in 1973.

"Wojtyla first wanted to make sure it wasn't a bluff," the source said.

"He asked it not be reported anywhere -- he said he would deal with it." The then cardinal had explicitly requested the alleged affair be kept strictly under wraps, he added.

Thomas Doyle, an American former Catholic priest, canon law scholar, and the author of one of the first reports of Catholic clergy abuse in the United States, said Gutowski's investigation was groundbreaking.

It showed that John Paul II knew this problem existed even before he became pope, he argued.

The broadcast of the investigation in traditionally Catholic Poland comes soon after a Polish-based Dutch journalist, Ekke Overbeek, made similar accusations.

Overbeek's book, Maxima Culpa, is due to go on sale in Poland this week.

Over the past two years, and amid several reports of abuse of minors in the Polish church, the Vatican has sanctioned several high-ranking church officials for having covered up paedophilia by members of the clergy.