US Coast Guard vowed yesterday to prevent fuel from leaking from a Shell oil rig that grounded in Alaska after breaking free from tugboats towing it in heavy seas.

The Kalluk mobile drilling unit was being towed to Seattle when it broke free on New Year’s Eve and washed ashore near Kodiak Island, some 480 kilometres southwest of Anchorage.

The rig has some 150,000 gallons of ultra-low sulphur diesel and roughly 12,000 gallons of oil and hydraulic fluid, according to the far northwestern US state’s KTUU television station.

There is no sign of leaks, but further checks were being made as authorities considered how to salvage the structure, the Coast Guard said after US senator Lisa Murkowski visited a Command Centre set up for the incident on Tuesday. “Senator Murkowski shares the Coast Guard’s desire to protect the pristine Alaska environment and response personnel,” said Rear Admiral Thomas Ostebo in an update posted online yesterday.

“Everyone involved in the response effort has the same objective: to safely recover the Kulluk without injuries or impact to the environment. So far, response personnel have demonstrated great resourcefulness and adaptability to the weather and other challenges in a very diffi-cult operation.”

Eighteen crew members had already been evacuated from the rig before it broke free late on New Year’s Eve, KTUU reported. By Tuesday it was described as “upright and rocking with a slow, but stable motion.”

Oil company Royal Dutch Shell said three people suffered minor injuries during the response to the Kulluk’s grounding, according to the television station.

“The extreme weather onditions and high seas continue to be a challenge, said Shell incident commander Susan Childs. “Our priority right now is maintaining the safety of our response personnel and evaluating next steps.”

Kodiak Island is a few hundred miles from Prince William Sound, where the “Exxon Valdez” oil tanker spilled around 40 million litres in March 1989.