LONDON (Reuters) - An investor survey showed the chance of Italy leaving the euro zone over the next 12 months at 19.3 percent on Tuesday, the highest reading since the poll started in June 2012.

The survey by Frankfurt-based Sentix comes ahead of the country's referendum on constitutional change on Sunday, which could unseat the government of Prime Minister Matteo Renzi and stoke a nascent banking crisis.

Over 1,000 institutional and retail investors were polled between 24-26 November. Last month's poll saw Italy for the first time overtake Greece as the country most likely to leave the euro zone, with a 9.9 percent chance seen.

The chance of any country leaving the euro zone stood at 24.1 percent, well below a peak of over 70 percent seen at the height of the euro zone debt crisis in 2012.

(Reporting by John Geddie; Editing by Jamie McGeever)