Ice floe halts Shell's new Arctic well September 11, 2012 -- Updated 0117 GMT (0917 HKT) Shell began work on its controversial Arctic project Sunday An ice floe forced the company to halt work on Monday Shell says it can safely drill off Alaska's coast Environmental groups say a spill there would be catastrophic (CNN) -- An ice floe forced oil giant Royal Dutch Shell to call off its preparatory drilling off Alaska just a day after the controversial work started, the company announced Monday. The drifting chunk of ice, more than 32 miles long by 12 miles wide, forced the drill ship Noble Discoverer to move off the planned well as a precaution, company spokesman Curtis Smith said. But the ship will be re-anchored within the next few days, and drilling will resume, Smith said. Shell began work on its planned well in the Chukchi Sea, about 90 miles off the Alaskan North Slope, on Sunday. The Interior Department granted the company permission to begin "certain limited preparatory activities" -- including work related to the installation of a blowout preventer -- on August 30. Shell's plans had been held up by BP's disastrous 2010 oil spill in the Gulf of Mexico, which prompted a review of offshore drilling plans. Environmental groups argued against the project, warning that a spill would be difficult to plug and clean up in the remote and inhospitable Arctic. Shell says it's working at far less depth and lower pressures than the BP well that erupted off Louisiana, destroying the Deepwater Horizon drill rig and killing 11 men aboard. But Steve Oomittuk, the mayor of the Alaskan coastal town of Point Hope, said he's keeping a wary eye on the Shell operation and has concerns about what the future will bring. The U.S. Geological Survey estimates more than 90 billion barrels of oil and nearly 1,700 trillion cubic feet of natural gas may be recoverable. CNN's Miguel Marquez contributed to this report.