The former Leeds and Great Britain full-back / outside half switched codes and moved to Cardiff to pursue a Union dream three years ago, but last week decided to trigger the opt-out clause in his contract to return to Super League.
Although Leeds have first option on his services, reigning champions Bradford are thought to have agreed a three-year deal for the 28-year-old.
Harris refused to commit himself to a decision on his future until his position at Cardiff was made clear.
A statement released through his solicitor read: 'Iestyn received notification that his contract with Cardiff Rugby Football Club was to be terminated.
'He is naturally surprised by the action of Cardiff and shall, over the next two days, consider his position.'
Cardiff Blues chief executive Rob Norster said on www.cardiffblues.com : "Iestyn Harris gave us notice of his intention to terminate his contract with Cardiff with effect from 1 September 2004. However, he failed to turn up to training on 15 June and we subsequently received a letter from his lawyer stating that the player would not be attending until further notice.
"We informed his lawyer that this was a breach of his contractual duties to Cardiff and requested that he returned to training no later than 21 June. Following Iestyn's non-appearance during this current week, we have now formally terminated his contract.