PARIS, May 11 (Reuters) - European telecommunications group Altice said first-quarter core operating profit grew 0.9 percent as its activities in Portugal and the United States offset a steep decline in profitability at its main French division, SFR.

Altice's adjusted earnings before interest, taxes, depreciation and amortisation (EBITDA) reached 1.62 billion euros ($1.84 billion), it said on Wednesday, in line with the average of analyst estimates in a Reuters poll of 1.63 billion.

SFR's adjusted EBITDA fell 9 percent to 851 million euros as France's second-biggest telecoms operator offered heavy promotions to attract customers.

Altice confirmed its full-year guidance for 2016 and reiterated that the closing of the acquisition of Cablevision Systems in the U.S. would occur in the second quarter.

($1 = 0.8785 euros) (Reporting by Mathieu Rosemain; Editing by James Regan)