Last Updated 8:46 p.m. ET
ROME The body of a woman wearing a life vest was recovered by Italian coast guard divers Saturday from a narrow underwater corridor of the capsized cruise ship Costa Concordia, raising the death toll to 12 in the week-old accident that has sent some light fuel spilling into the Mediterranean off Tuscany.
Coast Guard Cmdr. Cosimo Nicastro told The Associated Press that the victim was found during a particularly risky inspection of an evacuation staging point at the ship's rear.
"The corridor was very narrow, and the divers' lines risked snagging" on objects in the passageway, Nicastro said. To permit the coast guard divers to get into the area, Italian navy divers had preceded them, setting off charges to blast holes for easier entrance and exit, he said.
The woman's nationality and identity were not immediately known.
Before the corpse was found, 21 people were listed as missing. One of the women on the list is a Peruvian crew member, the others are passengers.
Early Sunday, instruments monitoring any movement of the Concordia indicated that vessel had shifted slightly, so search efforts were suspended for the night, Italian state radio reported.
On Saturday, CBS News correspondent Allen Pizzey reported that police divers have recovered the ship's "black box" - describes as a hard drive and two cameras - from the bridge of the Costa Concordia.
Three bodies were found in the waters near the ship in the first hours after the accident' since then the rest of the victims have all been found inside the Concordia, apparently unable to get off the ship during a chaotic evacuation via lifeboats and later by helicopters. Some survivors jumped off and swam to safety.
The Concordia hit a reef and ran aground on Jan. 14, while passengers dined, about two hours after the ship had set sail from the port of Civitavecchia on the Tyrrhenian Sea. Costa Crociere has said the captain had deviated without permission from the vessels in an apparent maneuver to sail close to Giglio, a Tuscan island, to impress passengers aboard.
Search and rescue efforts for survivors and bodies have meant that an operation to remove heavy fuel in the Concordia's tanks hasn't yet begun, although specialized equipment has been standing by for days.
On Saturday, light fuel, apparently from machinery aboard the capsized Costa Concordia, was detected near the ship.
But Nicastro said there was no indication that any of the nearly 500,000 gallons of heavy fuel oil has leaked from the ship's double-bottomed tanks. He said the leaked substance appears to be diesel, which is used to fuel rescue boats and dinghies and as a lubricant for ship machinery.
There are 185 tons of diesel and lubricants on board the crippled vessel, which is lying on its side just outside Giglio's port. Nicastro described the light fuel's presence in the sea as "very light, very superficial" and appearing to be under control.
Although attention has been concentrated on the heavy fuel oil in the tanks, "we must not forget that on that ship there are oils, solvents, detergents, everything that a city of 4,000 people needs," Franco Gabrielli, the head of Italy's civil protection agency, told reporters in Giglio.
Gabrielli, who is leading rescue, search and anti-pollution efforts for the Concordia, was referring to the roughly 3,200 passengers and 1,000 crew who were aboard the cruise liner when it ran into the reef, and then, with sea water rushing into a 230-foot gash in its hull, listed and finally fell onto its side.
Considering all the substances aboard the Concordia, "contamination of the environment, ladies and gentlemen, already occurred" when the cruise liner capsized, Gabrielli told a news conference.
Vessels equipped with machinery to suck out the light fuel oil were in the area, officials told Italian TV.
Earlier on Saturday, crews removed oil-absorbing booms used to prevent environmental damage in case of a leak. Originally white, the booms were grayish.
Divers resumed their search of the wreckage Saturday after data indicated the cruise ship had stabilized in the sea off Tuscany. Italian news reports said that the divers were also trying to locate the captain's safe, in case it might contain documentation useful to the criminal probe.
The Italian captain, Francesco Schettino, is under house arrest for investigation of alleged manslaughter, causing a shipwreck and abandoning the ship before all were evacuated. Schettino insists he helped coordinate the evacuation from Giglio's docks after leaving the ship when the Concordia lurched to one side.
The search had been suspended Friday after the Concordia shifted, prompting fears the ship could roll off a rocky ledge of sea bed and plunge deeper into the sea. An abrupt shift could also cause a leak in the Concordia's fuel tanks, polluting the pristine waters around Giglio, part of a seven-island Tuscan archipelago.