Authorities in Peru are investigating the deaths of more than 10,000 critically endangered Titicaca water frogs, whose bodies were found floating in the waters of Lake Titicaca.

The Committee Against Pollution of the Coata River reported the deaths, blaming pollution in the river that feeds into the lake, according to the BBC.

Peru's environmental agency (SERFOR) said statements from locals and samples found in the days following the incident indicated more than 10,000 frogs had been affected, within an area of around 50 kilometres.

SERFOR said "evaluation presence of solid waste and sludge formation was also observed".

The Committee Against Pollution of the Coata River said the Government had ignored their calls for a sewage treatment plant in the area, the BBC reported.

Frogs losing habitat and collected for food

Committee leader Maruja Inquilla said: "I've had to bring them the dead frogs — they have no idea how major the pollution is."

"The situation is maddening. Why is the state so apathetic? We need a sewage treatment plant now."

The Titicaca water frog is sometimes referred to as the "scrotum frog". ( Supplied )

Tititcaca water frogs are sometimes called "scrotum frogs" because of their wrinkly skin.

They are critically endangered and only found in the waters of Lake Titicaca.

The species' numbers have declined rapidly in the past few years, and the International Union for Conservation of Nature said that over the past 15 years, their population has declined by about 80 per cent.

They are collected for food, and their habitat is being lost and taken over by invasive species, including the North American trout.