Sisters Annamaria and Gianbattista, reportedly upset about their mother superior's authoritarian ways, scratched her in the face and threw her to the ground at Santa Clara convent near Bari in an incident in July that was kept quiet until now, Agence France-Presse reported.
Archbishop Giovanni Battista Pichierri tried to reconcile the nuns but finally decided in late August that they had "clearly lost their religious vocation'' and asked the Vatican for permission to close the convent.
Sisters Annamaria and Gianbattista moved to another convent, but Sister Liliana barricaded herself inside, refusing to leave, the reports said.
She suspected Bishop Battista Pichierri of planning to cede the convent to another community.
Liliana had been at the convent since its founding in 1963.