Companies seeking oil in the Arctic will need better technology to clean up spills onto ice and could face new hazards such as rougher seas caused by climate change, experts said.

The US Geological Survey estimated this week that 22 per cent of the world's undiscovered, technically recoverable reserves of oil and gas were in the Arctic, raising environmentalists' worries about possible impact on wildlife.

"The Exxon Valdez showed what a catastrophe can be caused by oil in the Arctic," said Ilan Kelman, a scientist at the Centre for International Climate and Environmental Research in Oslo. "The environment is remote, harsh and vulnerable."

The Exxon Valdez tanker ran aground off Alaska in 1989, spilling 42 million litres of oil off Alaska and killing thousands of birds and marine mammals.

Commercial Arctic oil exploitation began in Canada in the 1920s at Norman Wells but oil companies still lack full technology to handle spills, for instance, if oil seeps into or below ice floating on the sea.

"Responding to major oil spills remains a major challenge in remote, icy environments. This is especially true for spills in waters where ice is present," according to a 2007 report by the Arctic Council, grouping all governments with Arctic territory.

New clean-up technologies "have yet to be fully tested...spill prevention should be the first priority for all petroleum activities," according to the study for the US, Canada, Russia, Sweden, Denmark, Finland, Norway and Iceland.

Governments and oil companies are developing stringent safety standards to minimise risks of spills.

The WWF environmental group urged a moratorium on all oil and gas exploration until there was proper anti-spill technology and an ability to deploy clean-up equipment quickly to remote sites hit by winter darkness.

"We still lack technology to clean up spills in the ice and we can't do it in the dark," said Neil Hamilton, head of the WWF's Arctic Programme.

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