A Vatican court has found three El Salvadoran priests - including a prominent monsignor - guilty of sexually abusing minors and has suspended them from their priestly duties, the country's senior archbishop has announced.

Archbishop Jose Luis Escobar said Monsignor Jesus Delgado, the biographer and former secretary to the martyred Archbishop Oscar Romero, was among those convicted by the church court.

Last year Monsignor Delgado was among the three church representatives who announced in the Vatican that Pope Francis was promoting the late Archbishop closer to sainthood by giving him the title "Blessed".

The late Archbishop's assassination in 1980 by a state-sponsored death squad has been officially acknowledged by the civil authorities and led to last year's beatification ceremony in San Salvador which was attended by a quarter of a million people.

The promotion was a highpoint in Pope Francis' pontificate as he had personally "unblocked" the process of investigating Romero's "cause" after conservatives in the Vatican had suggested it would be imprudent to promote a man who was closely associated with radical movements in the Church.

The others who were convicted of abuse were Fathers Francisco Galvez and Antonio Molina.

They and Delgado were expelled from ministry after a criminal trial held at the Vatican found them responsible for crimes committed between 1980 and 2000.

No criminal charges have been brought against the three men by the El Salvador's civil authorities.

Pope Francis has said sexual violence against children will not be tolerated and has vowed to root out sexual abuse in the Church.