Rome, December 24 - Italian ex-premier Silvio Berlusconi brutally retaliated on Sunday against criticism voiced by Italian Premier Mario Monti in a Rome press conference earlier that day. "I had a nightmare...Monti again in Palazzo Chigi, (Gianfranco) Fini in the sewers, (Antonio) Ingroia in charge of justice," Berlusconi said on the RAI television program Domenica In. The one-liner pierced the idea of Monti occupying government headquarters once more - a prospect Monti said on Sunday he would consider if invited back. Monti's tenure as the head of Italy's technical government was interrupted this month when Berlusconi used his influence to undermine the government's political majority and declared he would run again for premier. Days later, Berlusconi said he would withdraw if Monti would head up a centrist coalition. This autumn, Berlusconi has vacillated publicly between seeking Monti's leadership as an ally and spurning Monti when he declined. On Sunday, Monti said he had "difficulty" following the "linearity" of Berlusconi's thinking recently. In his televised comment, Berlusconi also cut down his former coalition-ally Gianfranco Fini, who broke ranks with the former Berlusconi-led government, but remained president of the Chamber of Deputies after Berlusconi was forced to resign in November 2011. Antonio Ingroia is an Italian prosecutor and constitutional editorialist who asked for the indictment of one of Berlusconi's long-term collaborators, senator Marcello Dell'Utri, among roughly a dozen figures in an investigation into alleged mafia association by the state. Ingroia has since transferred from the Palermo court to Guatemala for a year to spearhead a United Nations investigation into drug-trafficking. Later in the television transmission, Belusconi threatened to walk off the program because program host Massimo Giletti interrupted with too many questions for Berlusconi's liking.