Friends and relatives of passengers who were on board a capsized Italian cruise liner carrying more than 4,000 people have turned to social media to search for loved ones and vent their anger and shock at the disaster in which at least six people died.

My cousin and my niece are still among the missing... someone said they were airlifted out but there are no traces...please let me know if you've seen them! wrote Sabrina Ottaviani on a Facebook forum, above a photo of her relatives.

The special Facebook page dedicated to the Costa Concordia was created after a British dancer who worked on the cruise liner used the social network to urge people to pray for her before she was rescued.

My name is Rose, it's Friday 13th and I'm one of the last survivors still onboard the sinking cruise liner off the coast of Italy, she wrote above a photo of herself stuck in the dark on the ship before she was airlifted to safety.

Divers have been combing the 114,500-tonne vessel for 16 people who are still unaccounted for. Rescue workers searching the half-submerged hulk recovered a sixth body on Monday, more than 48 hours after the ship capsized off Italy's west coast.

Social networks were buzzing with reaction to the disaster with particularly harsh criticism aimed at Captain Francesco Schettino, who has been arrested on suspicion of multiple manslaughter, causing a shipwreck and abandoning the ship before evacuation was complete.

Shame! To abandon the ship! Shame!, wrote one Facebook user, while others formed a group in the captain's defense.

Twitter users were posting the latest photos and videos of the vessel and keeping track of developments in the rescue.

A video of people waiting to be rescued on Friday, filmed by a passenger and posted on news sites and social networks, has brought web users close to the panic and trauma experienced during the catastrophe.

Several people were sharing their own memories online of previous cruises on the Costa Concordia and asking after staff members on the ship.

I was with my family on the ship two months ago and we wanted to know if the musician who used to play in the piano bar in Marsala is ok and if he's home, former passenger Enza Capitelli wrote on Facebook.

(Reporting By Catherine Hornby; Editing by Philip Pullella and Peter Graff)

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