SANTIAGO, Aug 3 (Reuters) - All five workers at Chile's El Teniente copper mine who were trapped in a collapse last week have been found dead, miner Codelco said on Sunday, as it vowed to investigate the cause and improve safety measures.

Codelco says four of the five workers trapped at its El Teniente mine have been pronounced dead, as rescue efforts continue following a powerful tremor that caused the mine to collapse last week.

SANTIAGO (Reuters) -Chilean copper miner Codelco has discovered the remains of one of five trapped miners at its flagship El Teniente mine, it said on Saturday, bringing the death toll from a collapse caused by a strong tremor on Thursday to two people.