Media photos of flames floating this week on the surface of the South China Sea appear to challenge a contention from China National Offshore Oil Corp. that an undersea gas leak it reported caused no environmental pollution.

Cnooc Ltd., a unit of the state-owned oil producer, said late Monday that a leak in an offshore pipeline prompted an emergency shutdown of production platforms off the coast of Zhuhai, in southern China.

"This incident neither caused any injuries nor environmental pollution, and the situation is under control," Cnooc said in its official statement.

The statement noted how the company "endeavored to release the natural gas" in the pipelines, setting a perimeter around the area to ensure the safety of vessels and residents.

What the company didn't say in the original statement was nevertheless demonstrated in dramatic television coverage and photos printed in newspapers. The gas was ablaze as it hit the water surface when released from the undersea pipeline.

In the photos, a bonfire of uncertain size appears to rage on the calm seas.

The China Central Television report on the matter explained that the fires were deliberately sparked as a safety precaution to release gas trapped in the long pipelines.

When asked about the state media coverage on Wednesday, Cnooc said the same in an emailed statement. The early evening statement noted that the flares were smaller than earlier in the day.

"The natural gas leaked from the offshore leakage point has been lit which helps lowering safety risk. The flame has also been reduced,"the email note said. "We would like to reiterate that the situation is under control."

It was the release of gas with a so-called "flame off" of unwanted fuel – an ocean version of the kind of flares often visible rising from towers high above natural gas depots and chemical companies.

Wearing a hard hat in the CCTV report, Gao Guangsheng, vice general manager of Cnooc's Shenzhen branch, opaquely addressed the flare-off during an on-air interview, without specifically mentioning the burning fuel.

Apparently referring to how gas being released from the under the sea sent water surging to the sea surface before it was ablaze, Mr. Gao said, "At that time there was only a column of water in the ocean. We've also monitored the pressure declining inside our pipes. So we immediately carried on. "

In its Wednesday night statement, Cnooc addressed questions about possible pollution by noting that no oil sheens have been observed by government monitors.

The oil and gas Industry considers venting fuel with flame-offs or flaring as a necessary bit of pollution. To others the sight of burning fuel often appears both polluting and wasteful.

It was unclear exactly where the Cnooc flame off took place, how long it lasted and whether there was only one. The gas leak itself was around 13 kilometers offshore from the Zhuhai terminal Hengqin, state media reports said.

Cnooc's undersea pipelines link two offshore platforms separated by 136 kilometers, one of which is 229 kilometers from shore.

Smoke on the water is powerful symbol. The 1969 ignition of Cleveland's Cayahoga River is credited with sparking a U.S. war on water pollution. Forty years later, the river in Northeastern Ohio was declared "teeming with fish."

– James T. Areddy. Follow him on Twitter @jamestareddy