(Recasts, adds comments from regulator, mine union, adds background)
SANTIAGO, Aug 30 (Reuters) - Chile's mining regulator on Tuesday ordered a halt to all operations at two major copper mines, state-owned Codelco's Chuquicamata and Freeport-McMoran Inc's El Abra, to investigate separate fatal accidents.
"We are concerned that today August 30 we had two accidents with three lost lives," said Rodrigo Alvarez, the head of the Sernageomin regulator, in a tweeted video comment.
"We've made two very difficult decisions for the industry. We've ordered the provisional and total suspension of both mines," Alvarez added.
Codelco, the world's No. 1 copper producer, suspended operations at century-old Chuquicamata after two workers were killed when the vehicle they were driving collided with a giant mining truck at around 1 p.m. local time (1600 GMT).
El Abra said that a worker died after an accident at its acid unloading terminal.
"All the workers are affected," the president of El Abra's union, Juana Mejias, said as she choked back tears. "This is really terrible and it hurts and is a product of excess workload in which the company cares about producing and producing and has pushed safety to the sidelines."
When asked about the union leader's comments, Freeport referred to an earlier statement that said the company reiterates its commitment to worker safety.
The accidents come at a time when mining companies across the industry have cut costs and laid off workers to cope with plummeting copper prices.
Century-old Chuquicamata produced 309,000 tonnes of copper in 2015. El Abra, which is 51 percent owned by Freeport and 49 percent owned by Codelco, produced around 147,000 tonnes of copper last year.
Reporting by Fabian Cambero and Antonio de la Jara; Writing by Anthony Esposito; Editing by Leslie Adler