* BHP cuts FY copper, coking coal guidance
* Eyes divestment of some U.S. onshore petroleum
* Narrows iron ore output to 265-275 mln/t (Adds details on U.S. petroleum, Elliott, quote)
By James Regan
SYDNEY, April 26 (Reuters) - BHP Billiton cut its full-year production guidance for coking coal and copper on Wednesday due to bad weather at mines in Australia and industrial action in Chile over the last quarter.
BHP also said it was progressing the sale of onshore U.S. petroleum interests at two key fields at a time when management is under pressure from activist shareholder Elliott Management to decouple the division from the company.
"Divestment of non-core onshore U.S. acreage is progressing, with the sales process well advanced for up to 50,000 acres of the southern Hawkville," BHP said in its fiscal third quarter operations report.
Additionally, BHP said its Fayetteville field is under review and that it was "considering all options including divestment."
The miner cut its guiance for full-year copper output by 17 percent to a range of 1.33 million to 1.36 million tonnes after a six-week strike at the Escondida mine, the world's biggest copper mine, that ended in late March.
Coking coal guidance was reduced by 9 percent to 39 million to 41 million tonnes, while BHP narrowed its iron ore output guidance to 268 million to 272 million tonnes.
The miner said shipments of Australian coking coal to Asian steel mills will be affected in the current quarter after a cyclone swept across eastern Australia in late March, cutting off rail lines to Pacific Ocean ports. (Reporting by James Regan; Editing by Richard Pullin)