A Dutch company that specializes in salvage operations says it will take weeks to remove the fuel from a cruise ship that capsized off Italy's coast.

The company says it plans to conduct a survey of the ship on Tuesday before the extraction process begins.

“It is a race against time to empty the fuel tanks on the ship after they finish the inspections to find, to give precedence to finding, any other passengers or crew members.”

The rough seas near where the Costa Concordia remains aground have raised concerns of a possible fuel spill. None of the nearly 2 million liters of fuel have leaked out, but anti-spill booms have been placed around the wreck.

“If the fuel starts to come out, it depends how much comes out, but we have learned from experience that even a little bit of fuel coming out is enormously difficult to control if it gets out of the containment booms that are put around the ship when there are these types of operations.”

Italian rescuers have been searching for survivors inside the wreck of the cruise ship, which hit rocks and capsized off the coast late Friday.

The search resumed Monday afternoon, hours after the Costa Concordia shifted on its rocky resting place in bad weather, sending divers fleeing to safety.

Six people are known dead and 29 others remain missing. The ship's owners, Costa Crociere cruise lines, are blaming the accident on human error by the captain.

A company spokesman says the captain was steering on an “unauthorized, unapproved” course before the ship got stuck. He says the captain steered too close to shore and made decisions during the emergency that did not follow company procedures, which are based on international standards.

Captain Francesco Schettino is in police custody, facing charges of manslaughter for allegedly abandoning the ship before all passengers were rescued.

Officials say that when the ship hit the rocks, passengers were ordered to put on life jackets and to board life rafts. However, passengers say the ship tilted so sharply and quickly that many lifeboats could not be lowered into the water.