The Serious Organised Crime Agency have been searching for the 30-year-old since he ran away from officers who visited his home in Purfleet, Essex in August 2007.
They were investigating drug-dealing offences.
Police had warned the public not to approach the professional kick-boxer, amid concerns he may become violent if confronted.
Hart's name was put on a list named Operation Captura last year, an investigation which focuses on criminals police believe have fled to Spain.
In September this year, one of those on the list, Michael Eddleston, surrendered to the British consulate on the Spanish island of Majorca.
The 27-year-old from Doncaster, South Yorkshire, was wanted in connection with three counts of illicit trafficking in narcotic drugs and psychotropic substances.
Anyone with any information on suspects on Crimestoppers "most-wanted" list can call anonymously from Spain on 900 555 111 and from the UK on 0800 555 111.