Mining giant BHP Billiton said yesterday it aimed to increase production and hike spending despite a 35 percent slump in yearly profit, citing "attractive opportunities" despite cooling in key market China.

The world's biggest miner also reiterated its commitment to the huge Olympic Dam copper and uranium project - delayed last week after it declared its first profit drop in three years - saying it would one day be a "very major" mine.

BHP chief Marius Kloppers said the firm hoped to spend US$22 billion on projects this year, up from US$20 billion last year, playing down the decision to scrap the Olympic Dam expansion in favour of a cheaper option.

"The combination of high exchange rate, high cost and high energy costs which we've got in Australia at the moment is a pretty unique set of circumstances," Kloppers told ABC television.

"If you can get any of those variables to change - plus we can make some technological breakthroughs - then we still think this is a wonderful ore body which is going to be a very major mine in due course.

"I would not be satisfied entirely if we didn't manage to grow volumes by about 10 percent or so over each of the next two years," Kloppers said.

Declaring a drop in annual profit to US$15.42 billion amid plunging commodity prices, BHP warned on Wednesday there would be no major project approvals over the next 12 months and the viability of more costly parts of its business was under review.

But Kloppers said "in reality what we are talking about is just slowing the rate of capex growth going forward", as he hailed China's prospects after Australia's resources minister said the commodities boom "over".

"I must emphasise that we're clearly going to be investing a great deal of money in the next 12 months," he said.

"The rate of growth in China may have slowed down a bit, (but) China's economy is very definitely still growing, and growing at the highest rate of the major economies in the world," added Kloppers.

"We believe that while the absolute demand growth for products is going to be lower than we've seen in some recent years we still believe there are very attractive opportunities for our company and indeed for Australia."

He said it would be a "couple of years" before the revamped Olympic Dam expansion went ahead, adding that BHP's major focus was in the energy and copper sectors, seeing them as key earners along with iron ore and coal needed for steel production.

Looking ahead Kloppers said potash fertiliser would be a priority, with BHP hoping it "can become a substantial profit driver for the company in due course".

BHP failed in a hostile takeover bid for the fertiliser group Canada's Potash Corporation in 2010.