Schlumberger Ltd , the world's largest oilfield services company, reported a 28 percent drop in quarterly profit, slightly beating Wall Street forecasts, and said the markets outside North America improved.

Schlumberger, whose planned purchase of peer Smith International is awaiting approval by antitrust regulators, said U.S. natural gas drilling should remain active in the second quarter.

Firmer oil prices attracted renewed interest in projects outside North America and margins were rebounding ahead of previous expectations, Chairman and Chief Executive Andrew Gould said in statement.

International margins appear to have bottomed and are now likely to resume a positive trend -- absent any exceptional circumstances, he said.

First-quarter net income fell to $672 million, or 56 cents per share, from $938 million, or 78 cents per share, a year earlier.

Excluding one-time charges, earnings per share were 62 cents, just above the 61 cents analysts had forecast, according to Thomson Reuters I/B/E/S.

Revenue fell 7 percent to $5.6 billion, slightly below the $5.69 billion analysts had forecast.

On Monday, its nearest competitor, Halliburton Co , posted a better-than-expected quarterly profit, helped by an unexpected boost in North America, though it said future growth would come from the Eastern Hemisphere.

Smaller rival Weatherford Ltd told a similar story when it reported results the following day.

(Reporting by Matt Daily, additional reporting by Braden Reddall in San Francisco, Editing by Lisa Von Ahn and Derek Caney)