"It's time for them to move on and I wish them all the best."
After a successful loan period, Spaniard Campo, 34, joined Bolton from Real Madrid in 2003, the same year Greek star Stelios arrived at the club.
Iranian international Andranik joined Bolton after impressing during the 2006 World Cup but has only made nine appearances this season.
Keeper Jaaskelainen missed the latter half of Bolton's season after he injured his back while warming up for Bolton's Uefa Cup tie against Sporting Lisbon on 6 March.
Long-serving Jamaican Gardner completed his ninth campaign with Bolton at the end of the season.
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