Dickov, 35, had loan spells with Crystal Palace and Blackpool last season after failing to establish himself in Sven-Goran Eriksson's first-team plans at City.
Brazilian midfielder Geovanni, formerly of Barcelona and Benfica, leaves at the end of his one-year contract, and Belgian striker Mpenza departs after 16 months with City.
City have also released Roberto Mancini's son, Filippo.
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