Once ConocoPhillips gets approval to build a pipeline to the National Petroleum Reserve in Alaska, interest in the region should increase, U.S. officials said.ConocoPhillips last year was denied a permit to build infrastructure needed to link production facilities in Alaska. Washington said it was reconsidering the permit after the company appealed a decision by the U.S. Army Corps of Engineers.Robert Abbey, director of the Interior Department's Bureau of Land Management, told Bloomberg News that Washington hoped the corps of engineers would allow Conoco to proceed with its pipeline plans."I think once that approval is granted that we would see a higher degree of interest in leasing within (the reserve)," he said.The National Petroleum Reserve in Alaska, owned and managed by the federal government, is estimated to hold as much as 896 million barrels of oil and is seen as critical for maintaining the flow of oil through the Trans Alaska pipeline.A so-called low-flow impact study produced by Alyeska Pipeline Co. found the Trans Alaska Pipeline has an expected service life of 10 years given anticipated declines in oil flows from the state.U.S. Sen. Lisa Murkowski, R-Alaska, said the report is a clear indicator that more parts of Alaska should be opened to oil and natural gas exploration.U.S. President Barack Obama has said he would invite bidders to the Alaskan reserves as early as December as part of an effort to bolster energy security.