ExxonMobil has deployed more than 280 people to clean up an oil spill along the scenic Yellowstone River but their efforts have been hindered by flooding, the oil giant said Monday.

It said cleanup activities involving absorbent pads and vacuum trucks were focused on a 19-mile (30-kilometer) stretch of the river downstream from the pipeline spill with another 222 miles (357 kilometers) under surveillance.

"Daily aerial flights over the river are being undertaken to identify additional oil locations and monitor and direct cleanup activity," it said in a statement.

"We are also walking the parts of the shorelines where it is safe to do so... Given the current flooding and very swift river currents, we will need to wait until it is safe to get into some areas," it added, without elaborating.

Considered one of the most scenic Western rivers, the Yellowstone starts in northwestern Wyoming and flows through Yellowstone National Park, creating the famous Yellowstone Falls.

Although the spill lies downstream from the park, the river is seen as a major tourist attraction along all of its length.

The company insisted it was monitoring air quality and that there was no danger to public health from the spill, though it has not yet publicized the results of water sampling.

It also said that bird experts from International Bird Rescue had arrived in the area and that other conservation groups had volunteered assistance, adding that it had "not received any confirmed reports of impacted wildlife."

ExxonMobil said Sunday that between 750 and 1,000 barrels of oil had been leaked into the river, but the firm has not yet identified the cause of the accident.

The company apologized to local residents but insisted that it had "met all regulatory requirements" and that the pipeline had been inspected in December.