Squabbling ruling coalition parties in Italy must not halt their support for the government of Prime Minister Enrico Letta because a political crisis could cause "irreparable" damage, dpa quoted the head of state as warning Thursday. Letta is threatened by a scandal over the botched deportation of the wife and daughter of a Kazakh dissident, a looming tax fraud verdict against his centre-right supporter Silvio Berlusconi and ruling coalition rifts about tax policy. "The negative repercussions [of a government collapse] in our international relations and in financial markets would be immediate and could be irreparable," President Giorgio Napolitano said. Interior Minister and Deputy Prime Minister Angelino Alfano, the most senior cabinet member from Berlusconi's People of Freedom (PDL) party, is facing a no-confidence vote Friday on the Kazakh deportations, which the government has admitted were a mistake. Some members of the centre-left Democratic Party (PD), Letta's own party, are threatening to vote with the opposition, triggering warnings from the PDL that if Alfano is forced to resign, they would withdraw their support of the government. The PDL has also threatened a crisis if judges uphold a guilty ruling against Berlusconi, which would force him out of politics. Italy's top appeals court was due to hear the case against the former premier on July 30 but might take weeks to deliver its findings. Napolitano said it was "indispensable" to continue work on the economic and political reforms that are on the government's agenda and said its opponents were guilty of "unjustifiably underestimating" the consequences of its downfall. The head of state, 88, forced the creation of a PD-PDL grand coalition government in late April after the two rival parties relied on him to solve a two-month post-election deadlock and re-elected him for a second seven-year term.