A national park in central Italy is investigating the death of a rare brown bear during an operation to capture it.
Biologists at the park in the Apennine mountains had trapped the animal to fit him with a radio collar so they could track his movements.
But the male Marsican bear began to struggle to breathe as he was being sedated and died shortly afterwards, despite efforts to revive him.
Wildlife officials have described the loss of the animal as "very serious".
"This is a subspecies in danger of extinction that now counts only 50 individuals or little more," said WWF Italia, as it called for a review of capture procedures.
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The bear was captured in a tube trap on Wednesday night, as part of an authorised operation at the Abruzzo, Lazio and Molise nature reserve.
According to Italian media, the young bear was not the intended object of the operation and park staff were trying to capture a different animal.
The other bear, Mario, had wandered into a village at night, and was deemed to pose a risk to its inhabitants.
"It is the first time we have been faced with an anaesthetic emergency during a capture," Antonio Carrara, president of the national park, told media.
Although the protocol "reduces the risks for the bear to a minimum, they cannot be ruled out completely", he said.
He had "full confidence in the park's staff" and hoped that the post-mortem would "shed full light on the cause of death", he added.