Pope Francis has strongly denounced the Catholic priests and bishops who "defamed" Salvadoran Archbishop Oscar Romero even after his murder in a campaign that delayed his beatification until earlier this year.

Francis spoke off-the-cuff Friday to a group of Salvadoran pilgrims who traveled to Rome to thank history's first Latin American pope for beatifying Romero, long a hero to the continent's poor and oppressed.

Francis told them that Romero suffered martyrdom not only during his March 24, 1980, murder as he celebrated Mass in a hospital chapel, but afterward.

He said: "I was a young priest then and I was a witness to this: He was defamed, calumnied and had dirt thrown on his name — his martyrdom continued even by his brothers in the priesthood and episcopate."