MOSCOW- Oil and condensate production at the Karachaganak oil field in Kazakhstan operated by Karachagank Petroleum Operating (KPO) fell by 21% to 0.785 million tonnes in September from 1.028 million tonnes in August, two sources citing output data said on Thursday.

Output from the oil field is down due to planned maintenance that takes place from Sept. 16 to Oct. 10, KPO's representative said.

KPO's representative told Reuters that maintenance was taking place on gas preparation units and restart of the units is planned on Oct. 10.

Karachaganak is operated by Shell RDSa.L and Eni ENI.MI and its production accounts for about 13% of Kazakhstan's total oil and condensate output.

(Reporting by Alla Afanasyeva, writing by Olga Yagova;Editing by Elaine Hardcastle) ((Olga.Yagova@thomsonreuters.com;))