The Titan Micoperi salvage consortium said the diver, a Spaniard aged 41, was preparing the starboard side of the wreck for the installation of sponsons that will be used for the refloating in the spring. He was immediately assisted by his diving partner and transferred to operations headquarters where paramedics were on hand.
Emergency medical staff arrived at the site and the man was airlifted to hospital by helicopter, according to ANSA news service, which identified him as Israel Franco Moreno, a native of La Coruña.
The incident is being investigated by the authorities.
Both Titan Micoperi and Franco Gabrielli, the head of Italy's Civil Protection Authority and deputy commissioner for the Concordia emergency, expressed condolences to the diver's family.
Gabrielli added his appreciation to the men and women who have worked 'tirelessly in difficult and risky conditions' on the wreck for nearly two years.