Environment group WWF on Thursday urged three European banks to block Russian giant Sakhalin Energy's plan to build an oil drilling platform that the group claims could harm the endangered grey whale.

"WWF this week has asked European banks behind a Russian off-shore oil development to do their part to protect a population of critically endangered whales," it said in a statement.

"BNP Paribas, Credit Suisse and Standard Chartered are among the companies financing the project, which currently consists of two drilling platforms off Russia's Sakhalin Island," it added.

Sakhalin Energy Investment Company is planning to build a third platform, which the WWF says is "dangerously close to the key feeding ground of western grey whales."

There may be less than 130 such grey whales, including just 26 breeding females, the group said.

"The western gray whale is on the verge of extinction, and the additional platform, which was never part of the original proposal, sets a dangerous precedent for all future oil and gas projects in the region," said Colin Butfield, head of campaigns at WWF-UK.

"WWF is calling on the banks to take action and oppose the plans -- before it's too late for these critically endangered whales."

A meeting between whale experts, representatives of the three banks, as well as the Russian company is scheduled to be held next week in Geneva.