WASHINGTON — Interior Secretary Ken Salazar said Tuesday that it was “highly likely” that the agency would grant Shell permits to begin drilling exploratory wells off the North Slope of Alaska as early as next month.

Mr. Salazar, while acknowledging that the Arctic presented unique environmental and safety challenges for oil and gas operations, said he was confident that Shell would meet the Interior Department’s new standards for offshore drilling. He noted that Shell had successfully tested a new oil spill containment device in Washington State’s Puget Sound in recent days and said he believed the company’s claims that it could collect at least 90 percent of any oil spilled in the event of a well blowout.

“I believe there will not be an oil spill,” Mr. Salazar said in a telephone briefing from Trondheim, Norway, where he is participating in an international conference on Arctic drilling safety. “If there is, I think the response capability is there to arrest the problem very quickly and minimize damage. If I were not confident that would happen, I would not let the permits go forward.”

The Obama administration is on the cusp of opening a new Alaskan frontier in offshore oil and gas development as part of an energy strategy driven by a desire to expand domestic resource production and to answer Republican criticism that it is opposed to conventional energy sources. The Interior Department conducted a major oil and gas lease sale for the Gulf of Mexico this month, attracting $1.7 billion in bids. The administration has also issued a number of permits for major natural gas, solar and wind projects on public lands.