US officials have granted oil giant Shell conditional approval to begin drilling exploration wells in the Arctic Ocean from next year, a move swiftly slammed by conservationists as \"inexcusable\". The US Interior Department has opened the doors to Shell\'s proposal for four shallow water exploration wells in Alaska’s Beaufort Sea to start in July 2012, said the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) in a statement on Thursday. Final approval requires Shell to obtain permits from other US agencies including the Environmental Protection Agency, the US Fish & Wildlife Service, and National Marine Fisheries Service. \"We base our decisions regarding energy exploration and development in the Arctic on the best scientific information available,\" said BOEMRE\'s director Michael Bromwich. The agency would closely review the oil giant\'s activities to ensure they are conducted in a \"safe and environmentally responsible manner,\" he said. Shell welcomed the news, saying it added to the company\'s \"cautious optimism that we will be drilling our Alaska leases this time next year.\" Environmentalists, pointing to the vastly complicated task of drilling in the harsh Arctic environment and effectively cleaning up any spills in such conditions, however slammed the decision as \"dangerous and disappointing,\" saying it puts the remote region, its wildlife and native communities at risk. The move ignored a wealth of concerns raised by the same US agencies during the catastrophic 2010 BP oil spill in the Gulf of Mexico, said a statement backed by leading environmental groups the Center for Biological Diversity, Sierra Club, and Alaska Wilderness League. \"This is a disaster waiting to happen, but still BOEMRE is moving forward with Arctic Ocean drilling,\" lamented Earthjustice attorney Holly Harris. \"BOEMRE\'s decision to disregard science and gamble with a region that is crucial to endangered bowhead whales, seals, polar bears and other marine wildlife that Native subsistence communities rely upon so heavily is inexcusable,\" she said in a statement. President Barack Obama had in May, prompted by high gasoline prices, committed to annual oil and gas lease sales in Alaska\'s National Petroleum Reserve, directing the Department of Interior to conduct annual lease sales in the region.