Italy's Coast Guard are trying to free a sperm whale entangled in a fishing net off the Aeolian Islands, an archipelago located near the northern coast of Sicily.
The cetacean had been spotted in difficulty by boaters on Saturday, prompting the Coast Guard's intervention.
The operation has involved divers, biologists and several patrol boats.
Authorities said the rescue is difficult because of the animal's huge size and its "state of agitation", which does not allow for a continuative safe intervention.
Other sperm whales got rescued in the same area on July 7 after remaining trapped in similar circumstances.
The Coast Guard said it seized over 100 kilometres of illegal nets in the southern Tyrrhenian sea since January; such nets are similar to the one the sperm whale got trapped in on Saturday, it said.
The organisation said in a Facebook post it has ramped up efforts to fight illegal fishing.