Thiess will continue to deliver open cut and underground mining services in Australia, Asia, Africa and the Americas at 25 projects across a range of commodities, with the contractor generating annual revenues of more than A$4.1 billion.

Under the terms of the exclusivity agreement signed in July last year Cimic and Elliott will jointly control Thiess, which is part of Cimic's mining and mineral processing segment with mineral processing specialist Sedgman.

Sedgman pulls in about A$400 million of annualised revenues with normalised profit before taxes of about 10%.

In a statement to the Australian Securities Exchange Cimic chairman and CEO Juan Santamaria said the sale lets the company capitalise on the sector outlook and Thiess' strong performance.

"The transaction proceeds will primarily be used to strengthen our balance sheet through the reduction of debt, while also providing additional capital to pursue organic growth prospects as well as broader capital allocation opportunities," he said.

"Our retention of the remaining 50% reflects the ongoing strategic importance of Thiess to our business."