By Gabriela Baczynska
MOSCOW (Reuters) - Environmental activists were forced to abandon their occupation of an oil rig in the Russian arctic on Friday when they were hosed down by jets of icy water, cutting short their protest after 15 hours.
The activists, including Greenpeace's global chief Kumi Naidoo, climbed the Gazprom platform off Russia's north coast after reaching it in inflatable speedboats at about 4 a.m. (0000 GMT).
They took ample supplies and intended to stay for days, clinging to the side of the platform - Russia's first offshore Arctic oil development - in tents pitched on small scaffolds.
They retreated to a Greenpeace ship "to avoid unnecessary risk in these freezing Arctic conditions," the group said.
A witness on the ship said Naidoo suffered from hyperthermia after being sprayed with water from the platform. Activists said chains were dropped from above.
Gazprom declined to comment about the reports of hosing or objects being dropped on them from the platform.
"The hosing is now very intense ... but we are going to stick it out as long as we can," a Greenpeace Twitter account quoted Naidoo as saying earlier.
"Succeeded in our aim of drawing attention to Arctic destruction in Pechora Sea," he said in a later posting.
Pechora, part of the Barents Sea, contains the Prirazlomnoye oil field, estimated to hold reserves of 526 million barrels. Russia sees a successful launch of Arctic exploration as vital to maintaining its status as the world's top oil producer.
Gazprom said the protesters had violated a 500-metre (500-yard) security zone around the rig.
"They were invited to climb up to the platform to conduct a constructive dialogue," but refused, Gazprom said in a statement, adding that work continued as usual.
Development of the Prirazlomnoye field has been plagued by delays, cost overruns and construction difficulties. Crude is now expected to flow by the end of the year.
Environmental campaigners say the Arctic's extreme conditions - its remoteness, darkness, sub-zero temperatures, ice and high winds - would hamper emergency operations in case of an oil spill in an area with a fragile ecosystem.
"The only way to prevent a catastrophic oil spill ... in this unique environment is to permanently ban all drilling now," Greenpeace quoted Naidoo as saying from the platform.
Greenpeace plans to promote a resolution at the U.N. General Assembly that would declare the Arctic a global sanctuary to prevent any oil drilling and unsustainable fishing there.
A similar sanctuary in Antarctica was created 20 years ago, when the mining industry was banned from operating there. But with many countries jostling to exploit the resources in the increasingly accessible Arctic, such a resolution would face greater resistance.
Russian state-controlled oil giant Rosneft has concluded deals in recent months with Exxon Mobil Corp, Italy's Eni and Norway's Statoil to drill for oil in the Arctic and other areas.
BP, Shell and Total have also started or plan to start drilling for oil and gas in Arctic regions, spurred by high commodity prices and concerns about future energy security.
The Arctic is estimated to hold at least 32 percent of the world's undiscovered oil and gas reserves and the region is becoming more accessible as global warming melts sea ice.
(Additional reporting by Vladimir Soldatkin; Editing by Robin Pomeroy)