There are fears of environmental disaster as sea storms may cause fuel leaks from the cruise liner which ran aground off Italy's western coast, environment minister Corrado Clini said on Wednesday.

"The ship is positioned near an escarpment, and may sink into deeper water with consequent further damage of its structure and following leaks from the tanks," Clini told a press conference in Rome.

"In such case, the environmental damage would be unforeseeable," the minister said, adding 2,400 tons of fuels are still inside the 290-meter-long vessel, which although being a cruise liner can be compared to a "small oil tanker".

In fact, over the past 10 years most environmental disasters have been caused by cruise and merchant ships, he noted.

Electrical accumulators in the vessel also pose serious toxicity risks, Clini said, adding his government will declare an emergency in order to urgently implement all necessary procedures without compromising massive rescue operations still underway.

A specialist team from Dutch company SMIT is preparing to pump the fuel from Costa Concordia's 15 tanks, which will take at least two weeks, the minister pointed out.

On Wednesday, salvage work in the capsized cruise liner, which is lying on its side in shallow waters near the Giglio island 25 km off the Tuscany coast, has been suspended after the vessel slipped about one meter, local reports said.

According to Italian authorities, 11 people are confirmed dead and 22 still missing days after the cruise liner crashed into rocks last Friday after leaving for a Mediterranean cruise with over 4,200 passengers onboard, while chances of finding other survivors from the wreck are getting slimmer.

The Costa Concordia's captain, 52-year-old Francesco Schettino, was put under house arrest after being detained with charges of manslaughter and abandoning ship.

A phone conversation recording between him and local port authority chief Gregorio De Falco, released by local media on Tuesday, suggested the captain left the ship before all passengers had evacuated.