ASTANA, Oct 21 (Reuters) - Kazakhstan's Chevron ( CVX )

-led Tengiz oilfield, the country's largest, has been

undergoing maintenance which is due to be completed on October

24, Energy Minister Erlan Akkenzhenov told Reuters on Tuesday.

Tengizchevroil (TCO), Kazakhstan's largest producer, reached

record monthly output of 3.715 million metric tons, or around

953,000 barrels per day, in August at the field.