A Russian billionaire has agreed to pump $200 million into the controversial Atlantic Yards project in Brooklyn, a transaction that would make him the first non-Canadian foreign owner of a National Basketball Association team.

In exchange for his investment, Mikhail D. Prokhorov, 44, owner of the Onexim Group and Russia’s richest man, would receive an 80 percent stake in the New Jersey Nets and a 45 percent share of the arena where the team would play once it moves to Brooklyn. In addition, Mr. Prokhorov has the right to purchase up to 20 percent of the surrounding 22-acre residential and commercial development.