Grenada's agriculture minister, Gregory Bowen

Billionaire Mikhail Fridman and Lev Blavatnik, board members of BP Plc's Russian unit, have been sued by RSM Production Corp., based in Greenwood Village, Colorado, over claims they interfered with its oil and gas exploration plan.

RSM said in the lawsuit that the two men, a Russian lawyer and Grenada's agriculture minister are blocking the Caribbean nation from issuing an exploration license for rights won in 1996. The suit seeks $500 million in damages.

The defendants "persuaded Grenada to not issue such an oil and natural gas licence to RSM as required by an exclusive existing contract for highly technical, insignificant and flimsy reasons," RSM and Jack Grynberg, an oil explorer working with the company, said in the complaint filed Wednesday in federal court in Manhattan.

Latin America held an estimated 103.5 billion barrels of proven oil reserves as of December, about 8.6 percent of the world total, according to the BP Statistical Review of World Energy. London-based BP's Russian unit, TNK-BP, isn't a defendant in the case. TNK-BP is Russia's third-largest oil company after OAO Lukoil and state-controlled OAO Rosneft.

Fridman, the chairman of Alfa Group and Tyumen Oil Co., is Russia's second-wealthiest man with a fortune of $11.4 billion, according to a list published by Moscow-based Finans business magazine on February 13. Alfa Group officials didn't answer phone calls made Thursday after business hours.

Fridman and the other defendants are financing Grenada's defense in RSM's arbitration of the dispute, according to the suit.

"I don't even know" Grynberg, Bowen said in a telephone interview, denying that he had ever sought a bribe. Grynberg "breached" his contract with Grenada, Bowen said.

The case is RSM v. Fridman, 06-CV-11512, Southern District of New York.