BHP Billiton , the world's biggest miner, expects heightened volatility and the uncertain economic outlook to weigh on sentiment in commodities markets, with customers being more cautious in managing stocks.

The company also warned on Thursday that some of the firms it does business with are facing tighter access to trade finance.

Despite these challenges, we continue to be able to sell all that we produce and our counterparties continue to perform to contracted volumes, Chief Executive Marius Kloppers told shareholders on Thursday at the group's annual meeting in Australia.

His outlook was more cautious than at the group's annual meeting in London a month ago, where he said prices had softened due to global uncertainty.

After delivering a record $21.7 billion profit in the last financial year, shareholders on Thursday are likely to press BHP to buy back more shares, following a $10 billion share buyback completed earlier this year.

The company has said it would consider buybacks alongside potential acquisitions and it plans to spend $80 billion in the five years to 2015 to expand iron ore, coal, copper, uranium and natural gas production.

(Reporting by Sonali Paul; Editing by Narayanan Somasundaram)

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