Story highlights Many feared dead as rough weather makes rescue efforts more difficult

More than 550 people have died crossing the Mediterranean into Europe in 2017

(CNN) Rescue workers have been battling for more than 24 hours in a bid to save as many as 1,800 migrants stranded on boats off the coast of Libya, according to charities leading the operation.

The Migrant Offshore Aid Station (MOAS) said in a statement they "believe there have been deaths," but it is not clear how many people have drowned.

So far rescuers have pulled 453 people to safety, but were forced to suspend the operation overnight with their rescue vessel the Phoenix running at full capacity.

The charity's founder, Christopher Catrambone, said yesterday: "Nobody has ever seen anything like what we are witnessing this weekend."

He later described in a tweet carrying a dead child on board the ship at Easter.

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