Royal Dutch Shell is pushing ahead with plans to explore for oil in the Arctic Ocean near Alaska this summer despite opposition from environmental groups.

The Anglo-Dutch oil major is preparing "an armada of 25 vessels" to begin a two-year program to explore two to three wells in the Chukchi Sea off the coast of Alaska, Chief Financial Officer Simon Henry said on Thursday.

"We are currently on track. Some of the permits are issued at the last moment," he told reporters.

Although Shell had to pull out of the region in 2012 after an oil rig ran aground, the Arctic oil reserve "remains a massive value opportunity," Simon said.

Shell has submitted plans to explore the Arctic to the U.S. Interior Department after the Obama administration last month upheld a 2008 Arctic lease sale, clearing an important hurdle for Shell.

The Department of the Interior will now consider the company's drilling plan, which could take 30 days.

Shell has lined up the necessary equipment and vessels to deal with any mishaps, which Henry said are of a "very low probability".

Environmental organizations fear that an oil spill would be destructive for an ecologically sensitive region and extremely hard to clean up in a remote area with rough and frigid seas.