SANTIAGO (Reuters) - Chile's state mining giant Codelco, one of the world's largest copper producers, fell further behind its production target in May, an internal document obtained by Reuters showed, underscoring the challenge to revive output at a 25-year low.

The mining firm, which has yet to publicly release data for May, produced 103,100 metric tons of the red metal in the month, some 8.6% below its target of 112,800 tons, the previously unreported June document revealed.

The firm produced 484,500 tons of copper in the first five months of the year, 6.1% off its target, the document showed.

Codelco, which is battling hard to revive production, did not immediately respond to a request for comment.

Codelco, which posted production in April below 100,000 tons for the first time in at least 18 years, has been hit by a deadly accident at its Radomiro Tomic in March, which led to a stoppage at the site amid the investigation of the incident.

The company's CEO has pledged that it will boost output this year after its worst performance in around a quarter of a century in 2023, affected by delay to major projects. The company has shaken up its leadership in recent months.

It is also pushing ahead with its new Rajo Inca project to extend the life of its small Salvador division and plans to begin partial operation of an expansion of its El Teniente underground mine in October-December this year.