At present, the company's oil and gas arm, Houston-based BHP Billiton Petroleum, operates shale oil production in Eagle Ford and Permian Basin operations in Texas.

Talking to investors in Barcelona recently, Mackenzie was quoted as saying it aims to increase its oil output by 66 percent to a daily production of 200,000 barrels by 2015.

But he said: "We are not a new player in oil and gas industries. BHP entered the business in the 1960s.

"We just didn't choose to form an integrated industrial chain from upstream to downstream. We have kept ourselves in the upstream business."

Zhang Tieshan, a senior analyst from the industrial information provider Mysteel.com, said that falling iron ore prices have had a huge effect on the profits of global miners, including BHP, Rio Tinto PLC and Vale Ltd.

"It makes good sense for BHP to tend to its oil and gas business, against the background of shrinking iron ore demand from China," he said.

"Although India's economic growth will create new iron ore demand on the international market, it will not be big enough to make up for China's slowdown."

And China's growing number of automobiles and other vehicles will ensure a growing demand for oil, Zhang said.

"So it is not hard to understand the benefits for companies like BHP to grasp these new growth opportunities."

However, experts expect BHP and other international players to continue to be hugely influential in the iron ore sector.

"China's iron ore demand will continue to grow even though the growth will slow," said Li Xinchuang, deputy secretary of the China Iron and Steel Association.

China will import up to 800 million tons of iron ore this year, he said. At present, up to 70 percent of China's iron ore consumption depends on foreign supply.

Mike Henry, BHP's head of technology, marketing and health and safety, added that iron ore prices will gradually decline over time.

That decline in prices and demand, he said, was mainly caused by increasing supply from new mines put into operation as well as China's economic slowdown.

"Chinese steel production over the past decade was growing at more than 15 percent annually, 1.5 times its GDP growth. We expect this growth going forward to be half the GDP growth, so steel production will grow only at 3 percent to 4 percent annually in the following years," said Henry.