The Federal Anti-Monopoly Service said Wednesday that it was investigating the country's second-biggest oil producer, LUKoil, on suspicion of barring a smaller rival from using its pipeline in the Komi republic.

A more liberal access to pipelines is one of the key goals that the competition watchdog is pursuing. It is also seeking a government decision that would make Gazprom more accountable in running its pipelines.

A small oil producer, Nobel Oil, complained that a LUKoil unit banned it from shipping its associated gas, a byproduct of oil production, via a LUKoil-owned pipeline, the Federal Anti-Monopoly Service said in a statement.

"Having studied the situation, the [service's] Komi branch saw signs of a breach of the law in LUKoil-Komi's actions," the government watchdog said.

Pipeline shipments of gas fall under the law that defends competition, it said. The anti-monopoly service demanded that both sides submit documents about the matter by Sept. 12. A service spokesman declined to elaborate.

LUKoil considers the pipeline its private property, a spokesman said. "Perhaps, we have the right to decide who we give access to," he said on condition of anonymity, citing company policy.

LUKoil will submit the documents by the deadline, the spokesman said.

A Nobel Oil official said that company president Grigory Gurevich was unavailable for comment Wednesday.