Boston archbishop Cardinal Sean O'Malley has expressed dismay at the report that Ronald Paquin, a 72-year-old former Massachusetts priest who was convicted of raping a 12-year-old child, has been released from prison.

"We are disappointed in today's ruling, particularly with concern for Ronald Paquin's victims and all others who have experienced the reprehensible crime of the sexual abuse of minors," he said.

O'Malley urged Paquin's victims to come forward so that new cases could be filed for him to remain locked up in jail.

Paquin was sentenced to 12 to 15 years in prison, and he completed his sentence in May, officials said.

Psychologists revealed that Paquin admitted to having molested at least 14 boys before he was arrested, officials said, according to the Boston Globe.

Paquin was freed after the two medical specialists determined he does not currently meet the legal criteria for sexual dangerousness, despite his history, the officials said.

Darren Duarte, a spokesman for the state Department of Correction, said Paquin was released, but he was not authorised to say where he has gone.

Court records indicate that Paquin planned to go to "the new Long Island shelter" if released or "a shelter for older men" near Boston Medical Center before eventually moving to Maine, where he would seek sex offender treatment, the Boston Globe said.

Back in 2002, Paquin pleaded guilty to raping a child, scandalising the Roman Catholic Church, according to Charisma News. He was one of the first few priests who were arrested in light of the Catholic Church's sex abuse scandal, which pinned down members of the clergy for sexually assaulting children while bishops covered up the scandal. Paquin, who served in Haverhill, Massachusetts, was stripped of his priesthood in 2004.

He pleaded guilty to three counts of raping a child, starting in 1989 when his victim was only 12 years old. Paquin completed his sentence earlier this year, but prosecutors in Essex County, Massachusetts still thought that he is a "sexually dangerous" person who must be confined.

From 1950 to 2013, the Roman Catholic Church in the US had 6,400 clergy members who faced sexual assault accusations. The church's estimate revealed that around 100,000 children have been victimised.

During his visit to the country last month, Pope Francis condemned the sexual abuse scandal, saying that "God weeps" for the victims of the clergy. He committed to hold those responsible for the heinous acts accountable for their actions.