Peter Berdowski, chief executive of Royal Boskalis Westminster, made the estimate and said the operation is "without precedent," Britain's Daily Telegraph reported Friday.
The Dutch company, which won the contract to remove fuel from the stricken cruise liner, is one of six bidders for the contract to remove the ship that has lain off the coast of Tuscany since running aground in January.
The newspaper said some rival bidders have proposed cutting up the cruise liner, which would be less costly.
Carnival Corp., owner of Costa Cruises, said it could take up to year to remove the ship.
Thirty-two people died after the ship capsized Jan. 13 off the island of Giglio on the first night of a six-day Mediterranean cruise.