A barge carrying one million gallons of petroleum naphtha caught fire and spilled the product in Houston Ship Channel on July 20 after colliding with another barge in Texas, the U.S. Coast Guard said.

The Coast Guard closed a section of the Houston Ship Channel from mile marker 348 near Bolivar Peninsula, but the incident is not affecting ship channel traffic, a Coast Guard spokesman said.

The channel is part of the Port of Houston, one of the busiest seaports in the United States.

As one of the most important oil shipping lanes in the United States, it allows barges and cargo ships to supply crude to more than a tenth of the nation's refining capacity and the export of refined fuels to international markets.

The collision occurred around 1:20 a.m. (0620 GMT), when both the barges were being hauled by tug boats and one of the tugs lost power, according to a report on the website of Houston's Channel 13, an ABC affiliate.

The barge that caught fire after being ruptured by the collision had been extinguished by a Houston Fire Department fire boat, it said.

The U.S. Coast Guard said it was not sure if the spill had any environmental impact. There were no reports of injuries.

In June, a section of the channel was briefly closed following the release of up to 23,000 gallons of naphtha after a cargo tank on a barge was damaged.

In March, there were two separate collisions on the waterway within the space of one week, with brief shutdowns of the channel.

The Ship Channel is a 55-foot (17-meter) deep pathway for barges and deep-draft ships cut into the floor of Galveston Bay, which averages 20 feet (6 meters) in depth.

Small barge collisions are not uncommon on the busy waterway, particularly as traffic has increased lately due to a surge in exports of refined fuels. However most incidents are cleared up quickly and major spills are relatively rare.