City release Petrov, Sylvinho and Benjani
Petrov, 31, moved to Eastlands from Atletico Madrid in 2007, but frequent injuries have restricted his opportunities and he spoke out against former manager Mark Hughes last season.
Benjani, also 31, was another Sven-Goran Eriksson signing and joined the club after a successful spell with Portsmouth, but he had found first-team opportunities limited and went out on loan to Sunderland in February.
Former Arsenal and Barcelona defender Sylvinho, 35, joined the club on a one-year deal last summer but made only nine starts as he struggled to keep pace with the Premier League.
A statement on the club's official website read: "Martin Petrov, Sylvinho and Benjani are senior players who will leave City this summer. All three are out of contract and free to negotiate deals at new clubs.
"Also released this summer are young striker Jack Redshaw, who is interesting Rochdale, goalkeeper Tobias Johansen and midfielder Karl Moore."