The principal of an historic foreign high school in Istanbul has become the first such figure in the history of diplomacy to be declared persona non grata.

Giuseppe Finocchiaro, principal of Istanbul’s Italian government-owned Ozel Italyan Lisesi (Liceo Italiano di Istanbul), is the subject of the unprecedented move made by Turkey’s foreign ministry, labour union Tez-Koop-Is (@tezkoopissndk) said on July 30.

The ministry acted against Finocchiaro in the wake of a 123-day strike by teachers at the school. The labour action was rare and protracted for Turkey's private education sector. An accord was brokered by the labour ministry to end the walkout, but the union then alleged that Finocchiaro and his Turkish deputy, Nida Intiba, subsequently launched a "retaliatory mobbing campaign" of harassment, isolation and the summary firing of 10 unionised teachers.

In response, the education ministry stripped both of the school administrators of their managerial licences. Acting at the request of the education ministry, the foreign ministry then formally designated Finocchiaro persona non grata under the Vienna Convention, revoking his diplomatic status and ordering him to leave the country.

Last December, IntelliNews reported how Italian teachers at the school earn salaries six times bigger than the salaries of their Turkish colleagues at the institution.

Liceo Italiano di Istanbul, or Ozel Italyan Lisesi, was founded as far back as 1861 during the Ottoman era. It is among schools for non-Muslim minorities in Turkey given permission by European governments to open during the 19th century.