UPDATE 1-World No.1 copper mine Escondida H1 output up 18 pct

* Escondida produced 533,242 tonnes of copper in 1st half

* Higher grades, mine activity, cathode output boost H1

SANTIAGO Aug 17 (Reuters) - Output from the world's largest copper mine, Chile's Escondida, jumped 18 percent in the first half of the year compared with the same period of 2011, to 533,242 tonnes on higher ore grades, mine activity and cathode output, the mine said on Friday.

Escondida, which is majority-owned by global miner BHP Billiton and extracts about 7 percent of the world's copper, this year has increased its copper output every month compared to the previous month, according to Chile's state copper commission Cochilco.

"This increase is due to better grades, a higher level of activity in the mines and a better performance of the cathode production plants," Escondida said in a statement.

The mine said it produced 366,205 tonnes of copper concentrate and 167,037 tonnes of copper cathodes.

The mine's copper output plummeted 24.6 percent in 2011 to 819,261 tonnes, its lowest level in nearly a decade, on sinking ore grades and a two-week strike.

BHP and Rio Tinto, which owns 30 percent of the mine, have approved plans for a $4.5 billion expansion of Escondida to boost output.

A new 152,000-tonnes-a-day concentrator plant and new mineral handling system will boost production to more than 1.3 million tonnes a year by June 2015.

BHP said in July that its copper production in the June quarter rose 15 percent from a year earlier to 312,500 tonnes, compared with a forecast of 311,200 tonnes from UBS.

Cochilco earlier on Friday reported Escondida had produced 533,200 tonnes of copper in the first half of the year, up 18.3 percent year on year.