Unknown assailants fired on a bus belonging to Freeport McMoRan Copper & Gold Inc.'s (FCX) Indonesian subsidiary early Wednesday, but nobody was injured in the attack, the company said.

"There were no passengers aboard the bus and no one was injured in the incident. Police are on the scene and investigating," PT Freeport Indonesia said in a statement.

PT Freeport said in the statement that its mining and milling operations remain unaffected by the attack, which took place around 7 a.m. local time near its operations area in the eastern Indonesian province of Papua.

Wednesday's shooting is the latest in a string of similar attacks on the U.S. miner's Indonesian operations in recent weeks.

PT Freeport operates the giant Grasberg mine in Papua, believed to contain the world's largest recoverable reserve of copper.

-By Reuben Carder, Dow Jones Newswires; 62 21 3983 1277; Reuben.Carder@dowjones.com