Australia’s Export Finance and Insurance Corporation has lent US$100mn to mining giants BHP Billiton and Rio Tinto to expand the world’s biggest copper mine.

The Escondida mine is in Chile’s Atacama Desert and the funds will help finance US$3.8bn worth of equipment upgrade, using US$100mn of Australian machinery.

Few details of the loan have been released, but Efic, Australia’s export credit agency, has defended itself amid accusations of corporate welfare from campaigners in the country.

“Efic’s operations on the commercial account are poorly-directed and inequitable,” Brynnie Goodwill, CEO of campaign group Jubilee Australia told local press, adding that smaller businesses should be made priority.

However, Efic’s spokesperson Peter Field has said the loan will support up to 80 smaller companies, since the companies will be purchasing equipment built on the Australian supply chain. “We are very pleased to be supporting a large number of Australian companies by providing finance to the project linked to Australian exports,” he says.