An escalating native title stoush linked to South Australia’s prized copper mines threatens to overshadow institutional support for BHP’s $9.6 billion OZ Minerals deal, which is expected to be sealed on Thursday with the endorsement of the world’s biggest investors.

Norway’s Norges Bank owns 4.9 per cent of OZ Minerals and will vote in favour of the takeover at a vote in Adelaide alongside two large North American pension funds, the California Public Employees’ Retirement System and the Florida State Board of Administration.