A Russian official said Monday that the sea off the remote Kamchatka peninsula may have been contaminated with toxic chemicals as Greenpeace warned of an "ecological disaster" for marine life.

Greenpeace has described how seawater off the far eastern peninsula changed colour and smell and "hundreds" of dead sea creatures including seals, octopuses and sea urchins washed up onto a black-sanded beach popular with tourists.

Testing around local bays and beaches showed above-permitted levels of phenol and petroleum products, the regional authorities said. 

Experts were investigating whether this was linked to "spills of some toxic substances," regional governor Vladimir Solodov said in a statement.

The 38-year-old governor said that inspectors on Tuesday would look at two military testing sites on Kamchatka that could be responsible.

"There are concerns; we will fully examine this tomorrow," he said.

The water pollution came to light late last month after local surfers reported stinging eyes and said the water had changed colour and developed an odour.

Solodov said surfers suffered mild burns to their corneas.

He added that divers had confirmed the deaths of sea creatures and pollution appeared to be spread over a wide area.

Tests on water of a river flowing into the bay showed it did not surpass legal limits, however.

Environmental inspectors and experts from a fisheries and oceanography research centre were set to continue tests.

The pristine peninsula is a popular destination for adventure tourism with its abundance of wildlife and live volcanoes.

Greenpeace said it has contacted state ecological monitors, the armed forces and the Prosecutor-General's office asking for an immediate investigation. 

Prosecutors and investigators announced they would carry out checks into whether a crime had been committed but have not any released findings.

The emergencies ministry said it was using boats and drones to monitor the coastline but added that "no pollution is visible."

The incident came as authorities urged tourists not to visit a live volcano on Kamchatka, warning eruption could be imminent.