Idemitsu Kosan Co.,the nation's second-largest oil wholesaler, said it has resumed talks with its founding family over merging with fourth-ranked Showa Shell Sekiyu K.K. The family's opposition has so far stymied a deal.

Japan's oil wholesale sector would be controlled by two dominant companies — industry leader JXTG Holdings Inc. and the newly merged firm — if the founding family were to bless the union.

The two oil companies aim to finalize the merger in spring 2019, sources close to the matter said.