The chief executive officer of Brazilian carrier TIM Participações – part of the Telecom Italia group – has stepped down effective immediately. Luca Luciani will be replaced by TIM’s group chief financial officer Andrea Mangoni in the short term.

TIM did not give a reason for Luciani’s departure, but the company’s stock price has been in decline since late last week, when Italian press reports speculated on the executive’s future.

Luciani had been named, but not charged, in a 2011 probe into allegations that Telecom Italia’s subscriber numbers were artificially inflated. Last year, Luciani worked at the parent company in Italy during a time when allegations were levelled at TIM that the company had issued around 1.5 million artificial SIM cards to inflate its subscriber numbers.

The probe has since ended, but the Italian press is now speculating that a prosecution may be imminent.