Anchorage - Less than a week after President Donald Trump took steps to put US Arctic and Atlantic waters back in play for offshore drilling, 10 environmental and Alaska Native groups sued Wednesday to maintain the ban on oil and gas exploration.The ban was a key part of former President Barack Obama's environmental legacy, aimed at protecting polar bears, walrus, ice seals and Native villages that depend on them from industrialization and oil spills. Waters of the Atlantic continental shelf also support whales, swordfish, bluefin tuna, sea turtles and businesses heavily dependent on the health of the ocean ecosystem, according to the lawsuit.In an executive order on Friday, Trump ordered Interior Secretary Ryan Zinke to review the withdrawal with the goal of expanded drilling.The federal lawsuit filed in Anchorage claims Trump exceeded his constitutional authority and violated federal law. No president before Trump has tried to undo or reverse a permanent halt to drilling in outer continental shelf areas, said Kristen Monsell, an attorney for the Center for Biological Diversity."With one careless stroke of his pen, Trump ignored the law and put our oceans at new risk of a devastating oil spill," Monsell said.The White House did not immediately respond to an email request for comment on the lawsuit. Trump on Friday said the executive order started the process of opening offshore areas to job-creating energy exploration."It reverses the previous administration's Arctic leasing ban and directs Secretary Zinke to allow responsible development of offshore areas that will bring revenue to our treasury and jobs to our workers," he said.Congress has the powerThe lawsuit claims Trump's order violates the US Constitution and the Outer Continental Shelf Lands Act.Congress has the power to regulate federal land under the Constitution. Lawmakers have authorised the president to halt drilling in unleased lands of the outer continental shelf but did not allow him to reopen areas, according the lawsuit.Likewise, the Outer Continental Shelf Lands Act itself does not authorise a president to cancel permanent bans, said Erik Grafe, an attorney for Earthjustice in Anchorage."It says nothing about the authority to undo those withdrawals," Grafe said. "No president has reversed a withdrawal in the past except for ones that have express end dates. President Obama's withdrawals were permanent."Obama halted oil and gas leasing in most of the US waters in the Arctic and key parts of the Atlantic in response to strong national opposition, Monsell said."The Arctic Ocean is not a rational place to drill for oil," Grafe said. "It's far too risky."