The Norway defender had his six-and-a-half-year stay at Craven Cottage ended on Tuesday, despite his contract still having a year left to run.
Hangeland, 32, said he was "disappointed beyond words" by his treatment at the hands of a club he captained for a number of seasons and played for over 200 times.
In a statement released via his agent, Jon Morland, the centre-back said: "Today I received the sad news that Fulham exercised an option to terminate my contract, effective immediately.
"I received such notification by e-mail with no representative from the club meeting with me at any point to discuss this matter. After six-and-a-half years of loyalty and hard work, and the last few years as captain, I am disappointed beyond words about this course of action.
"I would like to thank the wonderful Fulham fans for letting me share the best times of my career with them. I have been very proud to wear the white shirt at Craven Cottage.
"Needless to say, I still have a lot to give as a footballer and I'm looking forward to the next chapter of my career."
In response, Fulham released a short statement via their Twitter account, which read: "The Club would like to clarify that all personal protocol was followed and that Brede Hangeland was notified in the right way."
Sky Sports News understands that Hangeland's preference is to remain in England and play in the Premier League, after being unable to stop Fulham being relegated to the Championship last season.
Hangeland joined Fulham from FC Copenhagen in 2008 and played 214 times for the club, scoring eight goals.