"I would like to thank him sincerely for his efforts."
News of Mancini's return was warmly welcomed by Nerazzurri fans throughout the city on Friday.
Mancini, who is expected to sign a two-and-a-half year deal, won three league titles and two Italian Cups in four success-laden years with the Nerazzurri.
Expectations of Mancini's imminent arrival grew when former Inter president Massimo Moratti suggested a deal was done in denying reports he had played a role in influencing Thohir to choose Mancini.
"It was Thohir's idea," said Moratti, who gave up his role as the club's honorary president several weeks ago.
"I'm sorry for Mazzarri. Obviously he did everything he could to make it work."
Former Manchester City manager Mancini had been out of work since leaving Galatasaray last season and will be welcomed with open arms by fans frustrated by Inter's failure to perform to expectations under Mazzarri.
Mazzarri, who led Napoli to the Serie A runner-up spot in 2013, joined Inter in time for the start of last season but, despite glimpses of promise, had consistently seen his side underperform.
Inter, Italy's last Champions League winners in 2010, failed to qualify for the competition under previous coach Andrea Stramaccioni, and Mazzarri fared no better last season when Inter could only qualify for the Europa League.
Inter have won only four Serie A games so far this season while suffering heavy defeats to Cagliari (4-1 at home) and Fiorentina (3-0 away) as well as falling 2-0 away to relegation candidates Parma.
Inter currently sit ninth in the league, 12 points behind leaders Juventus.
-AAP
