* Pascua-Lama suspended by Chile court this month * Barrick said Wednesday it could stop spending on Pascua-Lama * Pascua-Lama accused of harming water supply, glaciers SANTIAGO, April 25 (Reuters) - Barrick Gold Corp said on Thursday the head of its South American operations has resigned, adding the company is shaking up its troubled Pascua-Lama mine with the aim of meeting Chilean regulatory requirements to unfreeze the project. Argentine Guillermo Calo, who was named Barrick's president for South America in July, has resigned, the company said. Robert Mayne-Nicholls, the general director of operations, and Rodrigo Jimenez, the regional vice-president for corporate affairs, have also resigned at the unit, Barrick added. A local court earlier this month suspended construction of Barrick's up to $8.5 billion investment, which straddles the border of Chile and Argentina, in a major blow to the world's top gold miner. The unpopular gold and silver mine is facing steep legal challenges and potentially the cancellation of its permit on grounds it destroys pristine glaciers and harms water supply. The Toronto-based miner had warned on Wednesday it could stop spending on Pascua-Lama if the timetable for resolving regulatory issues remains unclear. "The company is already taking all the possible steps to demonstrate its commitment, which includes updating engineering studies, elaborating performance plans and naming a new management team," Barrick said in a statement on Thursday. "Pascua-Lama's main priority is to re-start construction activity with the approval of Chilean authorities." The miner faces tough legal obstacles to complete the project, and even the possibility that its Chilean environmental permit might be canceled. Mining industry sources have pointed to poor management of the tricky, high-altitude project, with one source blasting it as "chaos." Barrick earlier this month tapped two high-profile mining executives to work on the project. Mega mining and energy investments have suffered major legal setbacks in top copper producer Chile recently, as environmental and health concerns grow and gain traction in courts. Many in the stratified country say the copper boom has not been fairly shared and has harmed the environment.