New York ? Oil prices eased Thursday but remained above $42 a barrel, a day after hitting a 21-year high in U.S. trading because of a threat by Russian authorities to shut down most of the production from that country’s largest oil company.

Russia’s Justice Ministry said Thursday it had lifted a freeze affecting three subsidiaries of the Yukos oil company. Yukos, which produces 2 percent of the world’s oil, had said those orders could shut off the production flow within days.

U.S. light crude fell 15 cents to $42.75 a barrel in trading Thursday on the New York Mercantile Exchange, easing off Wednesday’s 3 percent spike for the September contract to an intraday high of $43.05 a barrel — the highest level since the Nymex began offering the light, sweet crude contract in 1983.

While prices have eased a bit from Wednesday’s spike, analysts said the market could remain volatile as long as Yukos stands off with Russian authorities over an overdue multibillion dollar back tax bill.

“I’m still noting a bit of skepticism in the market right now,” said Phil Flynn, an analyst at Alaron Trading Corp. in Chicago, noting that the Justice Ministry decision does not guarantee that oil will continue to pump in the future. “The market is finally catching up with reality of Yukos’ situation. We were hoping it would go away quietly.”

The company says it does not have the cash to pay its $3.4 billion tax debt, and court orders have frozen assets that it could tap to raise money. Yukos officials repeatedly have warned that the company was being driven toward bankruptcy.

Analysts said oil prices might jump to $45, or even $50 a barrel, during the next several months before dropping back significantly.

“We’re certainly in a long-term bull market for crude oil,” said Tom Kloza, director of Oil Price Information Service, of Lakewood, N.J.