Six Greenpeace activists who scaled an Arctic-bound Shell oil drilling rig in the middle of the Pacific Ocean abseiled down on Saturday, with the oil giant securing a restraining order against the environmental group.

The protesters had been camped out for nearly a week on the 38,000-tonne Polar Pioneer platform, which they boarded 750 miles (1,200 kilometers) northwest of Hawaii after reaching it using inflatable boats from the Greenpeace vessel "Esperanza."

The rig, which is being transported by a heavy-lift vessel, is on its way to the Arctic as part of its exploration plans there.

"We're pleased the court agreed to grant a restraining order against Greenpeace," said Shell spokeswoman Kelly op de Weegh.

"It's unfortunate we had to pursue this legal action but we don't want a repeat of previous illegal stunts, including the group's illegal boarding on the Polar Pioneer drilling rig, this month.

"These tactics are not peaceful protests. They jeopardize the safety of the people working on board and the protesters themselves, especially aboard a moving vessel at sea."  

Shell was "open to an honest discussion about the challenges and benefits of exploring for energy in the Arctic," the spokeswoman added, "but we cannot condone Greenpeace's unlawful and unsafe tactics."

Greenpeace confirmed that the six activists -- from the United States, Germany, New Zealand, Australia, Sweden and Austria -- had abseiled off the drilling rig and into inflatable boats, before returning to the Esperanza, which had been stationed nearby.

It said they had left because of worsening weather.

Annie Leonard, executive director of Greenpeace USA, said: "It's astounding that Shell seems to think it has the right to jeopardize our environment and our economy, without being accountable to society.

"I thank the climbers for being society's eyes and ears on Shell’s rig, letting them know that millions of us are watching their every move, because there is simply no such a thing as 'safe' drilling in the Arctic."