A new kind of skin-eating fungus has been killing fire salamanders in the Netherlands at an alarming rate, European researchers said Monday.

The boldly colored yellow and black salamanders have dwindled rapidly since 2010, with just four percent of their original population left.

Based on an analysis of the dead salamanders, scientists reported in the Proceedings of the National Academy of Sciences, a US journal, that they have identified the cause as a fungus called Batrachochytrium salamandrivorans.

This salamander-eating fungus appears to be related to another kind -- Batrachochytrium dendrobatidis, or Bd -- that is blamed for killing more than 40 percent of amphibian species in parts of Central America, Austria, Europe and North America, or decimating about 200 species worldwide.

This fungus -- which may live in water or soil, or may be a parasite -- causes a disease called chytridiomycosis, which has been lethal to some frogs but not others.

"In several regions, including northern Europe, amphibians appeared to be able to co-exist with Bd," said study author An Martel from the University of Ghent in Belgium.

"It is therefore extremely worrying that a new fungus has emerged that causes mass mortalities in regions where amphibian populations were previously healthy."

Scientists are probing whether the new fungus came in to the country from another part of the world.

"We need to know if this is the case, why it is so virulent, and what its impact on amphibian communities will be on a local and global scale," said co-author Matthew Fisher of Imperial College London.

"Our experience with Bd has shown that fungal diseases can spread between amphibian populations across the world very quickly. We need to act urgently to determine what populations are in danger and how best to protect them."

Scientists said the fungus appears to pass among salamanders in direct contact, but found that it did not infect midwife toads, which can be vulnerable to chytridiomycosis.

Scientists took 39 fire salamanders into captivity for protection and to start a breeding program, but then half of them died between November and December last year. Only around 10 remain.

So far, the fungus appears to be isolated to the Netherlands.

But the emergence of the fungus "is worrying and warrants close monitoring, urgent risk analysis, and its inclusion in any monitoring program assessing amphibian population health," the study concluded.