MOSCOW, Nov 25 (Reuters) - Kazakhstan's largest

oilfield, Tengiz, has increased oil production in November 1 to

23 by 8.5%, month on month, to 787,300 barrels per day, but

still behind a planned level set by the energy ministry, a

source familiar with the statistics said on Tuesday.

Kazakhstan's Energy Minister Yerlan Akkenzhenov said earlier

on Tuesday that Tengiz was currently under maintenance again,

without providing details.

The Tengiz field is operated by U.S. oil major Chevron's ( CVX )

Tengizchevroil, which did not reply to a request for

comment. It underwent maintenance last month as well.

Overall oil production in Kazakhstan declined last month by

10% to 1.69 million bpd, still above the limits set by the OPEC+

group comprising the Organization of the Petroleum Exporting

Countries and other producers led by Russia.

Kazakhstan's OPEC+ output quota for October stood at 1.556

million bpd.

A production boost at Tengiz this year has been one of the

main reasons Kazakhstan has exceeded the quota.

In January, Chevron ( CVX ) started production at a $48 billion

expansion of Tengiz oilfield which will bring its output to

around 1% of global crude supply.

Tengiz is one of the world's deepest and most complex fields

due to high levels of sulphur and harsh weather conditions.