An international consortium of scientists said on Wednesday they had collected 1.5 million specimens of wildlife in an unprecedented mission to document the biological treasures of Papua New Guinea.

Marine invertebrates, fungus, algae, plants and roughly half a million insects were among the bounty from the three-month exploration of one the world's last biodiversity hotspots, they said at a press conference in Paris.

"This operation has no precedent in terms of scale, logistical demands and on-the-grounds skills," said Thomas Grenon, head of France's National Museum of Natural History, which spearheaded the 200-member effort.

"These are not skills you get from reading instruction manuals."

Biologists from 20 countries took part in the arduous mission, which focussed on ecologically-rich areas ranging from the Bismarck Sea to Mount Wilhelm, PNG's highest mountain.

PNG is the eastern part of the island of New Guinea, whose western part is Indonesia.

The island's rainforests are the third biggest in the world after the Amazon and the Congo.

Although New Guinea covers just 0.5 percent of Earth's landmass, it holds up to eight percent of the world's known species, according to the environment group WWF.

In the decade from 1998 to 2008, biologists identified more than 1,000 new species, including a frog with fangs, a blind snake and a round-headed dolphin.

"We brought back around 1.5 million specimens, and there will be many previously undiscovered species among them," said Grenon.

"On average, though, it takes some 20 years between acquiring a specimen and formally identifying it."