Moody’s cut Arco’s long-term debt rating.

The debt-rating firm, which recently put most major oil companies on a “credit watch” because of the collapse in oil prices, said Atlantic Richfield’s debt reduction “will be lower than previously anticipated” and its heavy reliance on Alaskan oil creates special tax-related disadvantages. Moody’s downgraded Arco’s long-term debt from AA-3 to A-2 but left its ratings on commercial paper intact. It said earnings from Arco’s refineries and service stations would remain strong. Arco called the action “unwarranted” and noted that Standard & Poor’s, the other big debt-rating firm, hasn’t downgraded the company’s ratings.