Cablevision Systems Corp. said Tuesday that its revenue and customer base slipped modestly during the third quarter as the company prepares to be acquired by European telecom giant Altice Group.

The Bethpage-based cable, telephone and Internet provider, which owns Newsday, said sales fell to $1.61 billion for the three months that ended in September, down less than 1 percent from the same period last year.

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The number of customers fell by 10,000, also less than 1 percent, to 3.1 million. It was, however, Cablevision's strongest third quarter in customer relationships since 2012, and the company grew its high-speed data customers by 3,000.

Cablevision, which announced in September that it had agreed to be bought by Altice for $17.7 billion, said net income dropped 68 percent to $23.1 million. Adjusted operating cash flow fell 12 percent to $417.4 million.

Tom Eagan, an analyst who covers Cablevision for Telsey Advisory Group of Manhattan, called Cablevision's third quarter "mixed." The drop in customers, he said, was not as severe as anticipated. "At the same time, revenue and cash flow were worse than we expected," said Eagan, who had forecast sales of $1.65 billion.

The Cablevision-Altice deal, which needs approval from regulators, is expected to close by mid-2016.

"In the meantime, together with Altice we are moving full speed ahead to obtain the necessary regulatory approvals, while we remain focused on delivering superior products and outstanding service to our customers," Cablevision chief executive James Dolan said in a statement.