A check was held after the World Wildlife Fund expressed concerns about possible negative effects of Rosneft's activities on grey whales, which visit the area.
"According to Rosprirodnadzor, a week-long inspection at the Lebedinsky site has not identified any breaches of environmental legislation of the Russian Federation," Rosneft said.
Rosneft is carrying out 3D seismic exploration work on the Lebedinsky licensed area of the shelf of the Okhotsk Sea adjacent to the Sakhalin-1 project.
Activists from various environmental groups have repeatedly voiced their concern about the possible negative impact of seismic work on the Okhotsk-Korean population of grey whales, listed in the International Red Book of endangered specie.
The Sakhalin shelf has nine oil and gas deposits in various stages of development with Rosneft, gas giant Gazprom, ExxonMobil, Japan's Sodeco, Mitsui and Mitsubishi, India's ONGC, Royal Dutch Shell working on the projects.
In December 2007, oil giant Royal Dutch Shell was forced to dilute its stake in the $20bn Sakhalin II project to let state-owned gas monopoly Gazprom take control.
That followed months of warnings from Rosprirodnadzor that Shell and its Japanese partners had broken the law by damaging forests and driving grey whales from their Sakhalin breeding grounds.
