Photos: Maersk chemical tanker in collision and spill, shuts Houston Ship Channel

The Maersk Carla was carrying a cargo of 216,000 barrels of Methyl tertiary-butyl ether (MTBE) and the leak is reported to have lasted about 90 minutes before it was stopped. It is not clear how large the spill is.

The two vessels collided in foggy conditions but US Coast Guard officials said it was too early to blame the weather for the incident.

“This is not a cargo chemical that is easy to clean up," Brian Penoyer, commander of the Houston-Galveston Coast Guard District was reported as saying.

The collision has closed part of the key waterway. “The Houston Ship Channel remains closed to all traffic from light 86 to the Fred Hartman Bridge,” the USCG said in a statement.

“There are 26 ships waiting to come inbound to Houston and 14 waiting to leave. The Coast Guard is working to help ensure that the remaining product in the ship is safely secured in order to begin reopening the ship channel.”

All the crew of the Carla Maersk are reported to be safe. A statement from Maersk was quoted as saying: “Consideration for the environment is of high importance for the AP Moller - Maersk Group and we are making every effort to avoid environmental impact. We are working closely with the US Coast Guard."