(Reuters) — BHP Billiton said on Thursday it hopes to fully divest its troubled U.S. onshore shale business in around two years and is also seeking a buyer for its nickel business in Australia.

The renewed push to unload both sets of assets, which the world's biggest mining company no longer deems strategic, comes as prices for oil and nickel enjoy a price resurgence.

"Nickel West is non-core, shale is non-core," Andrew Mackenzie, CEO, told reporters following the company's annual general meeting in Melbourne.

"We do consider we will see reasonable oil prices going forward, which is good for the businesses we retain and also the sales process," Mackenzie said.

BHP entered the shale business at the height of the fracking boom in 2011 and invested billions developing the operations. A subsequent fall in oil prices resulted in pre-tax writedowns of about $13 billion.

An exit from the shale business is one of the main demands of activist shareholders led by New York-based Elliott Management, who have pressed for a change of strategy by the global miner.

In shale, BHP recently sold a small portion of the onshore shale acreage, kicking off plans for a full exit over time.

"We really want to get this done in two years, ideally a bit less," Mackenzie said during the shareholders' meeting.

"What you have to do is build quite a comprehensive data room so that a wide range of people can come and look and kick the tires before they buy," he said.

Mackenzie made it clear there was little chance BHP would retain any exposure to shale.

"At this stage I see no way back," he said.