Oil giant Shell has resumed offshore drilling operations in Alaskan waters, the company said Friday, after one of its icebreakers was delayed for nearly two days by protesters dangling from a bridge.

Greenpeace activists were suspended from a bridge and in kayaks in the water for more than 40 hours in an effort to block the Fennica icebreaker from traveling to the Transocean Polar Pioneer rig in the Arctic Ocean.

Shell said drilling operations resumed Thursday at 5:00 pm (0100 GMT Friday) at the "Burger J" prospect in the Chukchi Sea, off the northwest coast of Alaska.

It said work would continue after the 116-meter (380-foot) Fennica icebreaker arrived at the rig.

"In the days to come, the team aboard the Transocean Polar Pioneer will work to complete the top portion of the well in anticipation of drilling to total depth once the Fennica arrives on site," the company told AFP in a statement.

"We remain committed to operating safely and responsibly and adding to Shell's long history of exploration offshore Alaska."

Fennica set off Thursday after it was blocked by the activists, including those suspended from a bridge in hammock-like devices. Other protesters were stationed on the bridge while some floated in kayaks in the water.

A US judge on Thursday threatened to fine the protesters for every hour they continued to block the Shell icebreaker.

Later Thursday, all of the hanging protesters had evacuated the site, but Greenpeace said it would continue to fight Shell and urged US President Barack Obama to stop Shell's exploration activities in the region.

"The 13 #ShellNo climbers have come off the bridge. Now all eyes are on President Obama to save the Arctic," the organization said on Twitter.

In May, Obama authorized oil drilling in the Arctic, a decision that infuriated environmental groups.

Greenpeace denounced Obama, and urged people to sign an online petition to block offshore Arctic drilling on Thursday.

"It's not too late. But we need to make our voices heard now," the group said in a statement.

"Ask President Obama and the Department of the Interior to show climate leadership and protect the Arctic by rescinding Shell's Arctic drilling lease."

Obama has called US oil production an "important" source of energy in defense of his move to allow Shell to drill in the Alaskan Arctic.

It is not the first time Greenpeace activists have stood up against Shell. In mid-June, protesters in kayaks tried to block the departure of a giant Shell oil platform from Seattle and keep it from drilling in the Arctic.

It is the first time Shell has conducted exploratory drilling in the Arctic since 2012, after facing several equipment and weather delays.

Fennica was in Portland for repairs after suffering an accident in the Arctic that left a hole in its hull.