A retired Argentine bishop seen as close to the Pope was on Friday sentenced to four and a half years in prison for sexual abuse.

A court in the northwestern town of Oran, where Gustavo Oscar Zanchetta, 57, was bishop from 2013 to 2017, ordered his immediate detention.

Zanchetta was convicted of "simple, continued and aggravated sexual abuse," with his offence aggravated by his role as a religious minister.

The trial in the town some 1,700 kilometres north of Buenos Aires began two weeks ago.

Zanchetta, who also worked as an advisor for the management of Vatican property, had denied the charges.

He was appointed to the Oran diocese by Pope Francis.

Once he has served his sentence, Zanchetta must sign a sex offenders register.

The charges were brought in 2018 by at least two seminary students.

The court heard evidence from two complainants, one of whom claimed the bishop had made approaches towards him and asked for "massages."

The Vatican has said that at the time of Zanchetta's resignation in 2017, there were no sex abuse claims against him.

The Catholic Church, which forbids priests from marrying, has been repeatedly rocked by child sex abuse scandals around the world over the last three decades.