The only companies who have a right to explore the Russian shelf are the state companies Gazprom and Rosneft, and they have declared that they are against letting any private companies work on the shelf, Interfax news agency reported on Thursday.

Gazprom's and Rosneft's directors Alexey Miller and Igor Sechin sent a letter to Vladimir Putin in which they expressed concern over plans "to liberalize access to explore parts of the continental shelf by private companies."

"As we have found out there have been attempts to amend the bill "On resources" and expand the rights of private companies by giving them licenses to work on the continental shelf," they wrote.

"In our opinion, this could harm the companies Gazprom and Rosneft as well as their shareholders," the letter said.

Miller and Sechin also asked Vladimir Putin to accelerate the process of giving their companies licenses to explore the continental shelf. "Rosneft applied for 14 licenses in 2010-2011. In June 2012 Gazprom applied for 29 licenses."

According to the current law "On resources" only companies that are 50% controlled by the state, and have over 5 years experience are allowed to carry out explorations on Russian resources.