Reuters reported the company as saying: "Corrado is leaving the business, this happened on his watch."
Read more: BT hit by key cut by credit agency
BT revealed earlier this week it was forced to write down the value of its Italian unit by £530m after years of "inappropriate behaviour". The news caused shares to lose a fifth of their value.
In today's third quarter results, the firm said "a number" of BT Italy's senior management were suspended and have now left the business.
"We have also appointed a new chief executive of BT Italy who will take charge on 1 February 2017," the company said.
"He will review the Italian management team and will work with BT Group Ethics and Compliance to improve the governance, compliance and financial safeguards, and reposition and restructure our Italian business."
Chief executive Gavin Patterson said the good progress being made across most of the business "has unfortunately been overshadowed by the results of our investigations into our Italian operations and our outlook".
Italian prosecutors have launched a criminal investigation and class-action lawsuits have been filed in the US on behalf of shareholders.
Yesterday, ratings agency Moody's changed the group's outlook from stable to negative.
Pre-tax profits fell 37 per cent at BT, covering the three months to the end of December. Headline revenues rose 32 per cent following the acquisition of mobile phone operator EE, but were down 1.5 per cent on an underlying basis.