KIEV, Sept. 26 - Russian oil company Lukoil is under investigation in Ukraine for creating a joint venture that may have illegally redistributed major petrochemical assets in its favor, the Prosecutor General Office said Monday.

Lukoil apparently managed to boost its stake in its Ukrainian petrochemical assets to 76% from 52% shortly after creating KarpatyNaftoKhim, the joint venture, in October 2004, the PGO said.