UPDATE 1-Rio files for IPO of North American coal assets

(Recasts to add details from paragraph 1)

LONDON, Aug 8 (Reuters) - Miner Rio Tinto PLC (RIO.L) (RIO.AX) said on Friday it had filed for a public offering of its North American coal unit, though it was also considering other ways of selling the assets.

Rio filed for an IPO of Cloud Peak Energy, which is made up of most of the North American coal assets of its Energy America unit, but said it would make a decision on whether to pursue a listing or another form of divestment once both options had been fully explored.

"Last November, we said that we would explore the possible sale of some or all of the U.S. coal assets of Rio Tinto Energy America," said Rio Chief Financial Officer Guy Elliott.

"We are in active discussions with a number of prospective buyers who have expressed strong interest in those coal assets," he added.

Second round bids for Energy America may be called in around the end of August, a source familiar with the matter said.

A variety of domestic and international trade bidders are interested in the unit, as well as some of the larger private equity firms, the source said.

A Rio spokesman declined to comment on the deadline for bids.

Rio itself is the target of a hostile takeover by larger rival BHP Billiton (BLT.L) (BHP.AX), a deal currently being examined by European Union regulators. (Reporting by Eleanor Wason and Mark Potter, editing by Will Waterman)