TNK-BP , Russia's third-largest crude oil producer, said it was aware of the urgency of environmental issues, such as the need for pipeline maintenance, following a barrage of criticism from the government over oil spills in Siberia.

Since the company was established in September 2003, environmental protection has been and remains a priority in TNK-BP's business activities, the company said on Friday.

During that time the company has invested $2.1 billion (1.3 billion pounds) in environmental programmes, including $285 million at Samotlor over the past three years.

Earlier this week, government officials attacked the company, half-owned by British oil group BP , threatening it with damages over spills in Western Siberia, including the huge Samotlor field, raising questions about TNK-BP's generous dividends.

TNK-BP accounts for 29 percent of BP's total production and 27 percent of its reserves. Dividends from jointly controlled companies make up about 14 percent of BP's profit.

TNK-BP shares were down 2.1 percent at 1040 GMT.

The criticism was a reminder of similar campaigns waged by the government against overseas enterprises, which led to foreign owners ceding stakes in hydrocarbon ventures in Russia, as was the case with Shell which was forced to cut its stake in the Sakhalin-2 project in 2006.

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On Thursday, natural resources and ecology minister Yuri Trutnev, who flew over TNK-BP's Samotlor field with an inspection, told a government meeting chaired by Prime Minister Vladimir Putin that he ordered a regulator to file a lawsuit against TNK-BP over the oil spills.

Energy minister Sergei Shmatko sided with his colleague by saying the company's dividend payout was too generous, hinting at the possibility of diverting cash previously slated for dividends for pipeline maintenance.

TNK-BP said on Friday: Even though the frequency of incidents is being steadily reduced, these figures demonstrate the urgency of environmental issues in the company's work.

Troika Dialog analysts said: Shmatko's reference to dividends seems to have shocked some investors yesterday. The key fear is that the company would be forced to change its generous payouts and, worse, invest in projects with low returns. TNK-BP's high dividend is simply a product of efficient investments and a refusal to make major acquisitions.

TNK-BP has been poised to pay a record-high dividend on 2011 results with the year-to-date payout to TNK-BP shareholders at $7.5 billion.

Analysts expected the company to announce remaining dividends for 2011 within a month.

Uralsib analysts estimate the possible additional expenses connected to the oil spillage could lower last year's dividend yield to 7.5 percent from an earlier implied 9.3 percent.

(Reporting by Vladimir Soldatkin; Editing by Dan Lalor)